He's not "dirty" in any sense, a spinning back elbow is not illegal in any way. The fact that it landed on the back of the head is a foul, but one what would have been inconsequential because Bonnar recovered enough to continue even without a pause from the ref.
HOWEVER, the 12-6s to Hamill (stupid rule or not) were illegal, as were the chin-butts to Bader's core. So if you want to use those as references yes, you can argue for a certain level of "dirtiness."
I don't think Jones is dirty, he's just undisciplined. Its a minute, but important difference.
Sig courtesy of that photo-matic magician limba
I went out the way that I fight. I went out on my shield. That’s it. Done. --Chuck Liddell
My goal is to end my opponent --Carlos Condit