If you are buying at non-foreclosure auctions beware of reserve or seller approved pricing. I have had clients purchase at these auctions thinking they would own the property with the winning bid only to have the auction company call and inform them that the reserve was not met or the seller didn't approve the price, then demand a higher price or their bid would be canceled.
Trustee auctions are true auctions (at least here) but I don't recommend them for newbies. There is no practical way to get title insurance, so if you miss something you're in a bad place. Many auctions are canceled or postponed within the last couple of days, so you don't have much time to research them unless you want to do a whole lot of work for canceled properties. The interiors are usually not accessible so there is no way to know the condition let alone do any inspection. Unlike on TV, many of the homes purchased through a trustee sale are still occupied by sometimes very angry people that you will have to negotiate with or evict.
I have bought many properties out of trustee auctions in Arizona over the past few years, but I have stopped recently because the HGTV and weekend seminar people have pushed up prices to a ridiculous level. I can purchase homes out of the MLS with title insurance and an inspection for the same that many people are paying at the auctions.