Since the seller has to pay listing fees on his auctions, it is foolish of him to cancel before the auction ends unless he has a strong reason.
If there are bids on an auction, the seller cannot revise it, so he has to cancel all bids (if he is wise he will contact each bidder with an apology and an explanation) before he can cancel, revise and relist. He loses his listing fee when he does this.
If eBay finds a problem with a listing(innocent double listing or outright fraud) they will end the listing and contact bidders. The listing fee is credited to the seller.
Some sellers are twitchy and do not realize that most bidding happens in the last few minutes of the auction. If there are not enough bids, or if the current high bid is lower than that seller wants, he may panic and cancel.
Some sellers do not realize they will be charged for the auction listing.
Some sellers do not realize that they only see the high bid and not the maximum bid. (I once won an auction by increasing my $200 maximum bid to $600 when a strong underbidder showed up late in the listing, pushing my high bid to $150. I still won at $400.)
The story is: Bid once, bid late, bid your maximum. If someone else beats you, he paid too much.
