I think to be on the safe side, I'd never click on any ad on my own Hubpages at all. However, I think it is all right to click on ads that are on other Hubbers pages. However, I'b be very interested in hearing what others have to say. Actually, there is an ebay ad on my own Hub that I want to buy! However, I think I'd go straight to Ebay (even though I wouldn't have found out about this at all if it hadn't been for putting my Hub together).