I was thinking about the phrase "Don't knock it till you try it", and how it doesn't apply in some situations. For example, Willy is doing drugs, and Joe tells him he's stupid to do so. Willy says "don't knock it till you try it." Yeah, obviously Willy's an idiot, but he may not think so. He may think, "I'm doin' drugs, and it's not hurtin' me. Joe can't talk because, not having done drugs, he has no way to know what he's talkin' about."
By that same (il)logic, one might say "don't knock it till you die from it." After all, how can you know whether something's going to kill you till you're dead? How far into "trying" something do you have to go before you've tried it enough to knock it?
Perhaps a good response to "don't knock it till you try it" would be, "I have tried it. I've tried it in the court of reason, and found it guilty."