Responding to your edit: I think kids are still figuring things out. I would not make any strong conclusions about big questions like this.

You run the risk of labeling one as "a liar" and the others as "brave" at an early age. That might just lead to a self-fulfilling prophecy.

I mean if they are just little kids, I suggest just trying do draw them out (read: by not trying to trap them) with more questions: "Really? You like this green tie? I like the green tie and the blue tie, too. I'm just wondering which one you like better. Either answer is good!"

If they are teens and you asked them to do something and they don't do it, then the consequences have to be tied to the behaviour, no?