Hello Kevin,
Are you saying a listing is repeatedly terminated before the end of the auction but after bids have been placed?
How close to the end of the auction?
If an item is relisted continually after the end of each auction, the seller may have many identical items.
Is this about a commonly manufactured item or some rare one-of-a-kind piece?
A seller can end a listing for any number of reasons. It is unwise to do it without just cause and if there are bids the seller may have to pay fees same as if the auction came to term. If you want to see ebay's official position on ending listings early, there is the following link:
http://pages.ebay.ca/help/sell/end_early.html
Would you be willing to post an item number for the thing in question? That way others here can have a look to see what you mean, maybe even follow some of the listings. Just the item number . . .