I have a few times. There are different types of auctions. The two types I've attended:
Foreclosure auctions. These are auctions that often literally take place on courthouse steps due to a lender foreclosing on a property due to nonpayment. You do not have the opportunity to look inside the house before bidding so you're buying sight unseen. You have to put down a large deposit if you win via cashier's check. You don't actually own the property until the sale is ratified by the courts as a foreclosure is a legal process though you are generally responsible for the property taxes for the property from the moment you win. Also, often times the original homeowners still live in the property so once the sale is ratified you have to go through the eviction process or offer cash for keys to get them to leave. So, lots of challenges and risk but you could actually end up with a good deal. You could also end up with a property that needs to be gutted from top to bottom after months of legal hassles. I wouldn't recommend this as a starting strategy for anybody.
Market Auction: There's probably a better term for this but anyone who owns a property can sell it via an auction. These are listed on the MLS through an auction house and you CAN go tour the property before-hand, often with a buyer's agent if you wish. The auction will often take place at the property although these days that's usually combined with an online auction that starts up to 2 days before the final bid is accepted. There is a suggested opening bid and a minimum bid increment.
When the physical auction takes place, bids will happen. The auctioneers will try to encourage action. When it seems like they have a final bid and no one is willing to increase it, they will often times go talk to the owner for a few minutes. The owner is under absolutely no obligation to accept any bid or to even sell the property. They will come back and give one last opportunity for bids. If there are some, it continues. If not, they'll announce the winner assuming the owner is happy with the result. Again, often times this requires a large down payment when you win to be held in escrow as things go to title. Also, there is usually a "hammer fee" which is a % of the total purchase price to be paid to the auction house by the BUYER.
Again, you can get good deals this way and you actually can tour the property beforehand so you generally know what you're getting into. In my experience, most properties that go to auction end up overpriced so I'd be prepared to attend a LOT in order to get something that worked on paper.
When I attended my first market auction with an experienced agent the advice he gave me was to figure out my maximum beforehand and stick to it (Seems obvious but people get caught up in winning). Also, don't bid until they are approaching your max. Wait until you're about 3 minimum increments away from your max, then come in with a 2X increment increase. Having someone come in late in the bidding process who is jumping by more than the minimum CAN help shut action down. This was just advice of course, no guarantees of results.
Regardless of the type of auction, once you own the property you can do anything legal that you want with it. So yes, you can fix and flip, or hold as a rental, or whatever.