Well, I don't necessarily think Paul is a massive cancer. But I would definitely put the truth somewhere in the middle. Anyone who flips on ANY team, let alone a respected, veteran-laden team like the Mavs is a massive asshat.
However, I do think CP3s at ude plays into this. It's obvious he has an ego every time he steps on the court. Like the dude as a person, but he might be the whiniest player in the league, and in the modern NBA that is saying a lot. His attention seeking antics are probably in the top 5, along with Kobe, Westbrook, LeBron, etc.
The repeated shuffling of blame that Paul does, where you can legitimately wonder if Paul ever thinks he's lost a game of his own accord rather than getting screwed by the officials is probably going to prevent him from becoming the greatest PG of all time. It could also prevent him from ever entering the truly legendary category of players. Such a shame. If he put his head down and just played ball, he would be so much scarier of a player. Maybe he'll grow up this year. Doubt it.