Imo, It is way too early to suggest that Ben Hendo "isn't marketable". Keep in mind, he's only been in the UFC for 1 and a half years, and only has two title defences. The key factor that has been the reason why he hasn't blown up yet, is the fact that has no finishes in the UFC.
Honestly, I think attitude has very little to do with how marketable you are as a fighter. Take Cain Velasquez for example. I see Bens attitude and approach to fighting as being similar to Cain. He trains very hard and generally doesn't have too many bad things to say about his opponent. But whats seperates them is the fact Cain in the past has ran through people in the first and second rounds, while Ben hasn't had that type of success in the UFC.
Givin the time, and the right string of wins, I think anyone can be marketable.