@Chrona - I'm talking about the expression in the idiom
being a fallacy, not that idioms are called a fallacy, man.
Also, "don't look a gift horse in the mouth" is talking about not looking at a free horses teeth for problems; basically, not to complain about free shit. I have no idea what you're talking about with the trojan or how relates to anything being discussed though; unless it was just something you felt like adding.