HomeBlog10 Advertising Mistakes That Will Destroy Your Credibility

10 Advertising Mistakes That Will Destroy Your Credibility

Author: Erin Sagin
Last Updated: November 27, 2023 | Copywriting

When it comes to paid search, advertisers only have one tiny snippet of copy—130 characters, to be exact—to win over new customers. You’re under tremendous pressure to create ads that are both engaging and informative, include a clear call to action, and stand out against competitors’ ads. Unfortunately, one sloppy grammatical misstep can counteract all your hard work and destroy your credibility. And if you violate Google Ads (formerly known as Google AdWords) policies, your ad will never even get approved.

To avoid giving searchers a negative first impression, be sure to double-check your ads to be sure you’re not committing these all-too-common advertising mistakes:

Advertising Mistake #1: Jumping Between Title and Sentence Case

top advertising mistakes

Lately, I’ve noticed that tons of people have a habit of capitalizing random words, seemingly with no rhyme nor reason. When writing ads, you should be using either title case or sentence case—no exception. What’s the difference? Sentence case is the standard format for most communications. With this method, only the first letter of the sentence is capitalized (along with any proper nouns).

Here at WordStream, we tend to favor title case for ads, as it typically yields higher click-through rates. With title case, you capitalize the first letter of the sentence, the first letter of any “major” words and all words with four letters or more.

nars ad in title case

Looks like NARS has got title case down pat.

Beware that excessive capitalization, such as FREE SHIPPING, and inter-capitalization, such as FrEe ShIpPiNg, are strictly prohibited in Google Ads and can spark an ad disapproval. Stick with sentence case or title case and you should be just fine!

Advertising Mistake #2: Neglecting to Use Commas

While they’re definitely useful, commas are the bane of my existence. Sprinkle in too many and your work becomes unreadable—too few and you risk dangerously altering the intent of the sentence.

come on people book

Either this was some weird foreshadowing or the editor needs a crash course in comma use.

Perhaps the most common misuse of commas is neglecting to include them after introductory clauses or phrases, especially when addressing an audience. This can dramatically change the way the reader interprets the sentence. I think we can all agree that “come on people” and “come on, people.”

i like cooking my family and pets

Uhh, ok Jeffrey Dahmer.

Commas also must be used to separate words in a simple series of three or more items. Again, failing to do this can result in a complete misinterpretation of the writer’s intent. If someone said “I like cooking, my family, and my pets” in the bio section of dating site, I’d probably be down to meet them. However, if their profile claimed, “I like cooking my family and my pets,” it would likely warrant a 9-1-1 call.

If you’re struggling to determine when to include a comma in your ad, a good (and completely unscientific) rule of thumb is to read the sentence out loud. If you hesitate or pause at any point while reading it, you probably need to insert a comma at that juncture. Here’s a more detailed primer on proper comma usage.

Advertising Mistake #3: Including Emoji

Believe me, I understand the temptation to use emoji characters in ad text. I’m guilty of sprinkling those cute little guys throughout my texts, tweets, posts—even emails! It may not be the most professional mode of communication, but you sure can convey quite a bit with these images.

emojis in tweet

WordStream’s Twitter account certainly has no shortage of emojis.

Unfortunately, adding emoticons in your ad copy is a major paid search faux paus. The Google Ads policy team has explicitly warned advertisers that this practice violates their policy guidelines. While some account managers have managed to evade disapprovals, it’s definitely not worth the risk. (Don’t listen to Larry.)

Advertising Mistake #4: Non-Standard Use of Numbers/Characters

ad with *s

Don’t bother trying to get creative with symbols and characters in your ad copy. Google considers this strategy to be “gimmicky” and, if you employ it, your ads will probably never see the light of day. Rather than using visual shortcuts to attract searchers’ attention, you should be striving to compose eye-catching headlines.

That said, there are a few exceptions to this rule. For example, if your brand or product names contain symbols (think: Arm & Hammer) or if you are legally required to include asterisks to indicate that conditions apply to your claims, you can use them in your copy (pending Google Ads’ approval).

Advertising Mistake #5: Using Improper Punctuation

comment with no commas

Failing to punctuate your sentence properly leads to a host of problems. Firstly, your copy will appear hastily composed and unprofessional. Even worse, it can lead to misinterpretation. For example, in the post above, does the writer mean to say “We have 2 hours to kill. Someone come see us” or “We have 2 hours to kill someone. Come see us”? These two versions carry drastically different sentiment.

Not only should you strive to use proper punctuation in your copy, you should try your best create sentences that fit within each description line of your ad. If you’re able to end the first description line with punctuation, your ad will be eligible for a mega-headline, whereby your headline and your description line are combined to create an extra-long header. Typically, ads with mega-headlines garner higher ad click-through rates, so you definitely want to create ads that are eligible for this!

Advertising Mistake #6: Substituting Slang Terms for Real Words

text slang terms defined

Back in the ‘90s and early 2000s, AOL’s instant messenger program took internet users by storm. As a middle schooler, I spent hours upon hours gossiping with friends and flirting with crushes via AIM. And anyone who was anyone conducted these conversations entirely in short hand. Back in those days, you was exclusively spelled u, too/to/two was always 2, thanks was thx…you get the picture. We then got even lazier and moved to initialisms like LOL, TGIF and BRB.

Nowadays, this slang has made its way into our day-to-day communications. However, it’s certainly not acceptable to incorporate into PPC ads. This is a major advertising mistake. Not only are these slang terms unprofessional, they’re also not universally understood. Some are regional, others are generational and all seem to be constantly evolving. Moreover, if Google detects such language in your ads, they will be automatically disapproved. Stick with real words—they’re worth the extra characters!

Advertising Mistake #7: Going Bananas With Exclamation Points


It’s important to convey urgency in your ad copy, but dousing it with exclamation points is not the best way to do this. Excessive use of exclamation points, be it multiple in a row (!!!) or throughout the copy (Bright pink lipstick! Luscious color! Buy yours today!), are deemed “scammy” by Google and will result in ad disapprovals. Instead, leverage more sophisticated tactics like ad customizers and enticing ad copy to woo searchers into taking action.

Advertising Mistake #8: Skipping Out On Spell Check

Just use it. Enough said.

Advertising Mistake #9: Misplacing Apostrophes

comic with misused apostrophes

Nothing gets under my skin more than a misplaced apostrophe. Remember, aside from conjugations, the main role of an apostrophe is to indicate possession. However, many people mistakenly use them to demonstrate plurality—a major faux pas.

The use case for apostrophes is simple. To show possession, plug in an apostrophe after your noun and tack on an s. However, things get a little trickier when the subject term already ends in an s (either because it is a plural or a singular word that ends in s). In this case, you can go one of two directions. If you adhere to the AP Style Guide, the apostrophe should appear after the s and there is no need to add a second s. For example, the kids’ parents were very mean. On the flipside, according to the Chicago style, singular nouns that end in s get an ‘s. For example, the Lexus’s bumper was dented. With words for which the plural term does not end in an s, like children, the apostrophe is applied after the word and an s is added.

There are two major exceptions to this rule that are downright confusing. The biggest culprit is definitely its versus it’s. Let’s set things straight. In this case, it’s serves as a contraction for it is. Its, without the apostrophe, is the possessive pronoun of it. Another confusing set is whose vs. who’s. In this case, who’s is a contraction of who is and whose is the possessive of who.

Advertising Mistake #10: Misusing of Homophones

friends ross complaining about homophones

Homophones are two or more words that have the same pronunciation, but different spellings or meanings. For those of us that think phonetically, this is an easy trap to fall into that can result in extreme embarrassment. Here are most frequently misused homophones to watch out for (definitions courtesy of Dictionary.com):


  • Affect: Verb: to have an effect on, make a difference to
  • Effect: Noun: a change that is a result of or consequence of an action or other cause

*Note that, at times, affect can be a verb and effect can be a noun, but the above definitions *usually* cover the bases.


  • Two: a cardinal number, 1 plus 1
  • Too: in addition, also; to an excessive extent or degree
  • To: preposition used to express motion or direction toward a point


  • They’re: contraction for they are
  • Their: a form of the possessive case of they used as an attributive adjective, before a noun
  • There: in or at that place


  • Whether: conjunction used to introduce the first of two or more alternatives
  • Weather: the state of the atmosphere with respect to wind, temperature, cloudiness, moisture, pressure, etc.


  • Your: a form of the possessive case of you used as an attributive adjective
  • You’re: conjunction for you are


  • Then: at that time
  • Than: used, as after comparative adjectives and adverbs, to introduce the second member of an unequal comparison


  • Complement: something that completes or makes perfect
  • Compliment: an expression of praise, commendation, or admiration


  • Complementary: forming a complement; completing
  • Complimentary: given free as a gift or courtesy

In Closing

Hey, we’re all human. In fact, this post probably has its fair share of grammatical errors. However, the more cognizant you are of these common slip-ups, the more likely you are to avoid them. Have you seen any other common grammar faux pas in ads?

Want more? Check out 7 Budget-Wasting Facebook Ads Mistakes (+How to Avoid Them)

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Meet The Author

Erin Sagin

Erin Sagin worked at WordStream for five years with roles in Customer Success and Marketing. She lives in California.

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