I have to say I sometimes watched Two and A Half Men when it was on during the day here, I never really minded it. I didn't really know anything about Charlie Sheen in real life though, and for the whole "How come you liked it on Two And A Half Men but not in real life?":
Two and a Half Men is a lot more toned down. He drinks a lot and brings home a different woman every night, but on TV loads of people bring home more women in a year than most people do in their lives in real life, just because its TV. So Charlie in comparison to them is not much worse, so in TV terms that's him being not much worse than the average womaniser (or even average single American guy, according to sitcoms). Also, Charlie on Two and a Half men isn't shown doing cocaine most of the time, and his arrogance and enjoyment of his lifestyle is portrayed rather comically.
Then there's the whole "liking a character on a TV show isn't the same as supporting them in real life". Tony Soprano and Cartman are good examples of this. Enjoying something on TV doesn't mean you have to like the people doing that in real life.
Also, for me (I don't know about anyone else) I always took Two and a Half Men to be a send up of that type of person - I didn't necessarily assume the actor agreed with what the character was saying any more than I assume James Gandolfini agrees with Tony Soprano.