question about the Auction House

Can a gamer be banned for buying a car from a cheating seller? If so, how would you know if a stranger on whose auction you were bidding had been or was about to be banned?

Yes, you can be banned for buying modified auctions. You can’t tell if someone is about to be banned, but there most likely won’t be any available auctions from someone who has been banned already. To avoid bogus auctions, don’t buy any car that has been aesthetically modded (missing parts, rims from other cars, neons, glow paints, etc.) or mechanically modded (ridiculously high/low PI for that car, high stats, impossible tunes, etc.). To be safe, remove the tune whenever you buy a car from the auction house.