One of the biggest gripes at GoDaddy auctions seems to be the high number of post-auction refunds. If a domain name is registered at a partner domain registrar, auctioned at GoDaddy Auctions, and then renewed by the domain registrant, the auction is canceled and high bidder is refunded. Any time spent on research and bidding is wasted.
Within the last few years, GoDaddy changed its own renewal policy to cut down on post-auction renewals and refunds. From what I understand, if a GoDaddy-registered domain name is not renewed 3 days prior to the start of the expiry auction, the registrant can no longer renew the domain name.