Trolling that ends in anything other than the subject feeling dumb or embarrassed, is no longer trolling
You could say a serial murderer killing prostitutes was trolling its victims, luring them into a place when he could kill them. Come on bro! The art of trolling is clear. It just gets a bad rap because someone always feels stupid as a result.
Actually, you know that feeling you get when you feel embarrassed for someone else? You know, that excruciatingly unbearable feeling you get when you cringe because you know the other person isn't even aware of their embarrassing behavior?
That's the feeling I get when I see people abuse the word 'troll'.