You have to understand the rules of a fish auction before you decide if it is a good idea to buy or sell any items there. I have yet to see an auction where you are not allowed to view the fish before the auction, and if you like you can come up and look at the fish while they are being auctioned.
I also have yet to see an auction where the name, phone number, and often the e-mail address of the seller is not included on the bag label. This is usually the information of a breeder when fish are involved, any fish I have sold at an auction, or anyplace else for that matter I will stand behind within reason. This is the way most everyone I know operates; it is nothing more than good business practice. The info on the bag is also free advertising, something anyone who breeds with the intentions of making any money likes. The only contact I have received from buyers is either fish care & diet related, or requests for more fish. This is fairly normal for local breeders selling at auctions.
You are getting locally bred fish, which are most likely already acclimated to your water conditions. These are the same fish that are sold in local shops, to be had at a bargain if you are savvy to local prices.
You also get to rub elbows with the breeders, any club member will point out the seller of a particular item, or give you the rundown on the seller if they are not available. Quite honestly, if a seller is selling something sub-par a club member will tell you this, often brutal honesty is involved.
I have sold many thousands of fish, mostly angels at auctions. I have also bought plenty of items, as stated there are many bargains to be had. One of the main purposes of auctions is to raise funds to operate the club that is running them. Without these clubs, and the information they share you would have less aquarists breeding, meaning less locally bred fish available at your lfs. Better shops will buy locally bred, they survive better in customer’s tanks, leading to a better business relationship for everyone involved. If shops can’t buy quality locally bred fish, whose shipping time is often less than an hour, they are forced to deal with shipping cross-country from fish farms, or internationally through importers.