For the sake of the English language, sarcasm means to say harsh or bitter things, generally using the trick of saying the opposite to what you mean, so as to hurt someone's feelings. I'd say that's negative. Perhaps you meant facetious.
Hi, i'm from Indonesia and i just want to say that i like Miyavi a lot!!!! He really has a great talent!! I don't care if all of you dislike him!!! Miyavi is impressive ya'know!!! I really love J-Rock!!!
It's fine to state your opinion, and there's realy nothing wrong with negative threads, though I see why they upset some people. But it really doesn't seem necessary to mock people. It just creates a lot of bad feelings, and solves nothing. Just thought I'd throw in my two cents.