Eh, calm down on the witch hunt here.
For one thing, no-one has any idea if the OPs car in question is the same as the one Sherlock 'jhegarty' Holmes found.
Even if it was, the dealer found nothing wrong with it, so it basically got a 'clean bill of health' and thus there is nothing to tell a prospective buyer.
And lastly, to the buyer I say this... "Tough". You thought you saw a bargain, but may not be as much of a one as you wanted. Them's the risks of buying private.
Once bitten, twice shy. Lesson learned. Quit yer whining.