"Curbstoners are scam artists. State laws prohibit private citizens from selling multiple cars or vehicles other than those titled to them. Curbstoning involves individuals who ignore these laws meant to protect consumers from unlicensed, unscrupulous sellers. Frequently, they sell vehicles reputable dealers won't touch-those with hidden problems in their pasts-problems that can affect both the safety and the value of these vehicles." -From the CarFax website
To do what you want to do requires a dealer license. In most states, to get that you need insurance AND a commercial address. To do this on the up and up, you are looking at slim profit margins. Most dealers don't send good cars to auctions, they sell them to other dealers or sell them on their lot. The real crap ends up at most of the local auctions. Now some of the bigger auction houses like Mannheim will have nice clean cars, but then you are bidding against some real competition who specialize in volume. Not saying it can't be done, but its a crowded and hard business to get into.