I recently started running some ads with Google Adwords. Been working nicely from the standpoint of sending visitors to my Etsy shop but I ran into a problem: the integration between Adwords and Google Analytics wasn't working right. Usually Adwords and Analytics integrate well to show you extra information about adwords campaigns bringing visitors to your site but it wasn't doing that for me. I tried tweaking various setting in Analytics and Adwords and finally figured out the problem.
I was using http://noadi.etsy.com as the link adwords was to use to send people to my shop, once I changed it to the direct link http://www.etsy.com/shop.php?user_id=6288550 it started registering the stats correctly. I think this is related to how Etsy handles urls for subdomains. I still use noadi.etsy.com as the url that is displayed on my ads but it's not where visitors are directed.
So if you're using Adwords to advertise your Etsy shop you might want to edit the ads so you get more accurate stats in Analytics.