I'm not going to give my entire life history just to look at a few items that I may or may not decide to bid on or purchase. I really believe that sites like this are simply phishing for people's information. Lord only knows what they do with it when they get it. If it's a real auction, you should be able to browse through their inventory, and supply your information if and when you decide you want to bid on something. So what if it shows up as a sponsored link on a trusted site, even viruses can do that. All it takes is one click.