We recently had an interesting question from a reader:
Can I run an AdWords campaign for my products listed on eBay? If yes can I link it directly to eBay?
The answer to this is a little bit tricky: eBay sellers are no longer able to submit products via their own merchant feed to Google product listings. eBay sellers have to rely on the eBay product feed to have their products pushed to the Google merchant feed. The same goes for Etsy and similar marketplaces. Assuming your products are showing within the marketplace in question’s merchant account, you can submit those products via AdWords product listing ads (PLA).
The way this works is that each marketplace is required by Google to have a multi-client account  and create sub-accounts for sellers (more information on Google’s policies on this here ). To actually link your product listing ad to a sub-account, you need to contact eBay (or any marketplace) to have them create a sub-account for you, which you could then link up to your AdWords account.
If you have the ability to list products on your own website, of course, you can avoid these issues entirely and create your own merchant account, and then simply link that account to your product extensions.
For more on product extensions, check out our Google AdWords Product Extensions Guide .