Sorry for double-posting, but I don't think a car has to be a lemon just because it was an excellent offer.
I bought an S-Class very, very cheap because the company that bought it (yep, no leasing, which was usually common since the 90s!) and went into bankruptcy. So the liquidator sold everything at low prices aiming fast and safe money for the creditors.
I almost do not dare to say it.. but that S-Class was a lemon..
But nevertheless, maybe there is a certain reason why you get a decent car for a low price and it's still not stolen or a shitbox.