Well, if you worry that your past interactions will color your old ones, I cant say that you are wrong. Some people will expect certain behaviors, arguments etc from you, and some may even treat you differently based on how you have conducted yourself.
But a lot wont. I used to be much more ignorant than I am not, and have said some colorful things in the past. But ive been here 5+ years now, and I can easily say that the forum members will treat you semi-fairly from thread to thread, even if youve said colorful things in the past.
In short. You're treating this forum too seriously, this is supposed to be fun, arguing and debating things are supposed to be enjoyable.