I don't like it when what they do is teabag/taunt spam. Overkill is OK, especially if they use appropriate moves, like Maxi's 2KB or Natsu's 2K. The conclusion of the match just looks better IMO. Single taunt, or multiple uninterrupted taunts are OK (though single preferred). That being said, I don't get mad when people teabag or taunt spam. Why should I care lol.
The problem is, that a lot of people do get really mad if you overkill/taunt/teabag, etc. You can do it with your friends and whatnot because you know them and they probably won't care, but usually, when your fighting online complete strangers, you get lots of hate.