OP
On the Internet, do as you like, but I usually find online chat is pretty offensive, abusive and utilizd mostly by bad players or idiots. I usually go the route of civility and let the cards and my play speak for itself. Plus, if you talk enough shit, the calling stations and fish will simply ditch and find a new table and then you've screwed yourself out of money.
Live, where ratholing and table ditching isn't allowed, I'd suggest you be respectful and concentrate on a good/positive table image. I've seen Internet types (not hard to pick 'em out) go into places like the Horseshoe in Tunica and try to verbally spar with some of the regulars there, let me just say that the parking lot can be a long walk...not kidding. Most of the time the guys talking shit in poker rooms have long live play relationships and getting involved can bring much more bad than good. There are some serious gamblers at some live tables and many aren't as casual about table talk as others. Live you are not anonymous and it's a different game.
JMHO