Basically what this guy said on the site Vohy linked:
Pay for bid sites are scams especially when the bid you pay for can only go up a penny… This forces you to pay more to bid. Also, the fact that the timer at the end keeps going up with every bid – the difference from an actual action house is that you DON’T PAY TO BID. The next part of the scam is that they own the item so if their bot wins the bid war they just keep it and re-list it so they no only get money from you for each bid, but now they still own the product…
I would feel sorry for the people getting ripped off by these sites, but they should have checked the “too-good-to-be-true” mechanism that any intelligent person has nowadays.