Maybe I should say to disable Adblock / Adblock Plus in FF or use IE. You won't even see the ebay cashback ads if you Adblock.
Well, for example yesterday I bought something from Buy.com using the bing.com cashback link and nothing showed up in my cashback account. I made the purchase using FireFox with my usual suite of Adblock Plus, NoScript, etc. I've tried using FireFox a few other times and the cashback never shows up.
When I've bought using IE, it always works as expected.
YMMV


