If the seller and shills are different individuals, you can assume they are probably friends from the same area of the country. The seller's geographic region is usually placed beside every seller's name. To obtain the bidder's geographic region, you can request such information from the auction. You can also determine whether the seller and shill are from the same ISP by looking at their email addresses.

Feedback

Looking at a seller's feedback might give you some clues as to whether the bidders at a seller's auction are shills. When looking at a seller's feedback, do you notice that the positive feedback is from the same bidders all the time. If the bidders are also auction sellers, do you notice that the same individuals are providing positive feedback. This alone is not enough to determine whether the bidders are shills. For instance, many bidders tend to bid and follow certain sellers whose auctioned items they wish to purchase or simply because these bidders like dealing with a particular buyer.

You should analyse feedback a little more closely. Is there inconsistency in the feedback. Do only the same individuals provide positive feedback while other different bidders provide negative feedback.

Bidders' Auctions

Shills tend to bid on partner's auctions. Shills also tend to bid on all items of a seller irrespective of what the seller is auctioning. Given that not all the same bidders will like all of the seller's items, this is one sign of which you should be aware.

Shill's Bidding Practice

Shills tend to bid early and bid high in an auction to set the tone for the auction. Try to determine whether the same bidders are bidding up the price of an item and then dropping out towards the end. Shills do not want to end up being the winner of an item since it defeats the process of shilling.