I don't get insulted, I just use it as a platform to explain how my gains are so much better than most people's, just because I don't take gear and usually eclipse most people on it.
My favorite are the juicers who come up to me and tell me what they're taking...then they wait for me to reply and let them know I'm on something, when I'm not. I could take the time to say how sad it is that most people need a drug to achieve much in a gym, but I feel bad for these guys usually. It must blow to know one of your better "achievements" in life, isn't even due to your dedication, but just some shots and pills. Sad beings.
In fact, I'll go right up next to many juicers to do an exercise and compare in the mirror. I dominate 90% of the time...BOOM! haha
Fucking Imitators man, gotta love em'.