Originally Posted by sonicslash
You back yourself in a corner when you make a face character that does heel things. Once you get a character like that over, it becomes increasingly difficult to turn them heel down the road. With the Internet it is already pretty difficult to perform a heel turn on a popular face character that doesn't even do heelish things. Look at punk, it took him a lot of segments to get people to boo him.
It's not because CM Punk was a 'badass' face that is impairing his ability to get heel heat, it's the fact that they are expecting the older audience to buy that he's a heel because of some stupid as hell storyline, and how he won't ever gain respect for being champ or beating Cena and still won't as soon as he drops the belt to Cena.
The best angle to turn a badass face to heel is to basically have them clearly sell out. Take an offer from a heel stable, take a kayfabe bribe to take a dive, something that completely goes against what made them a badass to begin with.
Or that's my opinion on the matter, and as others have pointed out, currently Ryback is something of a badass face.