I have not met Cameron Smith. What he is like off field I have no idea. I can only judge him by his on field actions and demeanour.
I do not deny he is a very talented rugby league football player. No denying it. However his seeming "win at all costs" demeanour sees him does stuff which annoys the crap out of me. Things such as constantly arguing with the referees whenever a decision goes against him or the Storm.
Granted other players do this too, but Cam takes it much further. When other players get waved away and accused of time wasting by referees, they rarely ever do so to him, often holding the game up whilst he remonstrates with them. It is that difference in treatment which annoys me - you either treat all players like Cam and stop the game every time to explain, or you wave him away after a brief explanation (p.s. I know what is in the rugby league rule book by the way on this matter).
His carry on field at the time of the Alex McKinnon incident was poor. McKinnon was in a bad way, but did Cam show one iota of concern for a potentially injured player? Nope. I was watching that game, his lack of sportsmanship was glaring at that time. He gives you the impression that he will do "whatever it takes", even if it means bending the rules, to win.
Then add on the media frenzy around him. It happened with Johns, Thurston, and Lewis (to name a few) whom whenever they did something decent on the field the media would all but cream themselves over it proclaiming it the best play ever even if it was something run of the mill. People make up their own minds about things and do not like having how they should feel rammed down their throats. It is why, in my opinion, Wally Lewis was so disliked in NSW during his glory years was because of the media reporting of him.
Coupled with that reporting is the expectation that because he is a good player we must respect and like him too. As such supporters at other clubs just find that expectation unbelievably unrealistic, which is why he is often unliked.