If you are a new bidder, you are probably not aware of the term shill. It is the plant in the audience who asks the question given by the lecturer, it is the guy in the demonstration who orders 10 of the snake oils and has a miraculous cure, it is the person who can suddenly walk at the evangelist meeting and on eBay it is the bidder who keeps bidding up your item to reach a higher level. If he wins, he doesn't pay for the item and it is relisted by the seller, but if he gets you to the price he wants, you pay 3 or 4 times more than you should have. The easiest way to catch one is to look at the bid history and click on to his name. If he hasn't bid for two years and comes out of the woodwork to bid on your item and keeps bidding against you, then there is a good chance he is a shill. Many of the bigh Power sellers have opened up numerous acounts. How many you don't know, but they often even have similar names, so the seller is actually the bidder upping your bids. I read a blog that this was prevalent in Mickey Mouse items and huge lots of Children's clothing and almost everywhere on eBay. Another way to spot them is to put the bidder in advaced search--search by bidder. If he is buying from the same merchants and never wins a bid but always raises the bid to above the price--you do not want to bid against him. I don't think you should make the maximum bid too high because sometimes they just want to get you up to the maximum. On a blog someone was bid up by 6 different buyers and when she looked them up, they all had not bid for years. They roped her in by letting her get one good buy. She reported them and they were kicked out, but the shills were not kicked out. She saw the same items a month later by a new store. There was a blog of a woman who bid on childrens lots and she showed the items she bid on and lost being resold two days later, but nothing was done. It takes many complaints to get it investigated and those who paid too much or didn't get the bargain they should have are none the wiser. There are legitimate buyers who want the same item too and will try to outbid you and that can be fun and exciting, but a shill bidder is just a con trying to rip you off. Avoid them and report them if you suspect it is going on. I am updating this as I have just read a blog by the seller. She brags about shilling up a bid because she will be selling the same item and doesn't want it to be considered cheap. The poor unsuspecting bidder paid $20 and she is bragging about the dishonesty on a blog. So you don't have to just worry about the store-you have to worry about --- who sells Barbie Dolls or others like her who think it is LOL funny to Shill bid and brag about it on the blogs.
I am updating this because eBay now only shows fake names of bidders. You really will not be able to see who is bidding against you which gives shill bidders carte blanche as no one can trace them. It will protect your identity which is a plus, but encourage more shill bidding which is a minus. Just be very careful on eBay and set a limit that you want to bid and do not go over it & do not put a high maximum bid