That depends. I care what people think only as long as what they think seems reasonable to me. Otherwise, I practice an extreme amount of ignorance. I'm that person, who when generic rebelious / immature person tells me off, just sort of gives them this knowing look and shakes my head, before walking away.
I speak my mind, with little regard for how other people think of me. I say what I believe to be the truth from my point of view, and if I'm wrong I don't feel so much as a ping of regret.
Sometimes, mainly on public video games I can come off as one heck of a jerk. But for the most part, what I want to say is not something mean or rude in any way unless blatantly provoked.
Basically, the rule when working with me is "Do it with some kindness in mind or it's a waste of time."