There's a big difference between someone saying 'you're just being a proper uppity fuck' and someone writing a medium length post describing what someone's perceived errors have been, before ending it with a pretty pointed 'goady little fuck' when that poster has long since left the thread.
It's dismissive, and comes across as a bit vicious. There's not much room for misinterpretation there.
Or someone saying (again without humour) 'see, the word twat was created for people like you'. Or similar.
No emoticons, just a defensive nastiness. Maybe they were right to be pissed off but a lot of people manage being 'goaded' without riposte, or at least without obscene riposte.
It's a bit like saying 'you wound me up so much I had to hit you in the head'.