The obvious flaw in pyramid schemes is that for you to make money you have to recruit new members. Eventually this becomes impossible and the pyramid collapses, with many people on the lower levels losing money. The bottom line is that you should be very careful of multi-level plans which ask you to pay to join, and even more careful if there is no product being sold. Personally, I think that any multi-level plan which asks you to pay to join is simply not worth it. The auction is very exciting.
People can post and bid on different items.
They are all generating different click-through ratios.