Ever since I first started to watch this show I began to carry a strong resentment towards [the character]Dexter and the ways he would justify his acts.
The one thing that has disturbed me even more is the atmosphere and general consensus by many of the fans which is very creepy. The millions who watch this show and look up to him as a vigilante, with wholehearted and noble intentions, on the side of the common person. All while believing they too can relate well with Dexter and maybe even share a few moments if they met the guy in person. When in fact they probably share nothing in common and are just as likely to end up on the his table.
That being said, I wouldn't spend one minute in a room with this guy. The only reason he murders people who circumvented the system is because it makes him feel as if he does no wrong since it doesn't break harry's code. A code which he has broken. Not to imply that it holds any legitimacy. It was just a way to separate himself from his victims and make him feel like he doesn't share any attributes with them. Which he does if you look at the number of innocent people who were ruined/killed, in a similar fashion that Dexter himself was, either directly/indirectly throughout the series.
tl;dr version: Dexter is mental and in no way is he the "good guy."