The context would be more instructive as to the level of venom the utterer wishes to infuse into it. I think if I were in a heated argument and five minutes into the shouting, he calls me a scumbag, I may just be so ticked off to hit the guy. Similarly, if my friend and I are joking around and while cracking up, he calls me a fucking asshole, I wouldn't be incensed.
That being said, if a stranger called me a scumbag, it would definitely get the anger train rolling.
Choo, choo.