I'm curious as the ways that the popular sites block spammers from siging up. For example I've tested two popular dating sites and one is easy to register and another deletes my account after 10-30 minutes no matter which IP, profile info I use. Can they see your computer's MAC address even if you use a VPN with a proxy? Or do they just have thousands of moderators? I think this is an important question so we know how to protect our privacy from unethical web sites we might visit.