It kind of depends on the situation. If you are a curmudgeon to everyone you meet, you will be known as such. If you are polite, you will be known as that, too.
If you are referring to the internet, just remember: You usually get what you give.
For me, how I treat others, no matter the situation, is more important to myself than those with whom I interact. If I am courteous, I generally feel better about myself. If I am rude or impolite, I feel uneasy after all is said and done. (Maybe not right away- sometimes I enjoy being curt, but it always comes back to haunt me later).