I've had a successful eBay affiliate website (it's a custom script not BANS based) running for months getting its only traffic from AdWords. I found a nice niche with keywords going for 0.10 and was able to convert a good percentage of the click to eBay sales. Things were going good until yesterday when I logged into AdWords to check my keywords and noticed about 25 of them had been disabled with a new minimum bid of 0.40 to $1.00. Nothing's changed on the website to explain Google's sudden dissatisfaction with my website. Granted the website has no original content but it's not just a simple dump of the eBay items, I've actually grouped the products in a more logical manner that makes it easier to find and shop for products. Did anyone else have this happen and what did you do?
there are all sorts of reasons why google does that, mainly it revolves around your landing page quality relative to your ad wording and the keywords you are bidding on. as always with google its all about relevance (keywords, ad, domain, landing page content etc) but also a "good experience" for the user so they look for things like contact info, privacy policy and so on. to get more in depth help you may be better off posting this question in the adwords forum. good luck