That began with Berto holding on to the hand. Instead of focusing on freeing the trapped hand, Guerrero punched with his free hand. Good for him.
Mayweather is just as dirty as every other great, and like the other greats he hides it better than your average fighter. Shoe stepping, headbutts, elbows, holding, leaning.... All the greats do it.
Ortiz did what he did to Mayweather because he was frustrated. That's it. He was starting to get popped, realized he had no plan b, threw the bull**** flurry out of desperation, the the headbutt out of frustration. Then he got his stupid ass laid the **** out. Rob isn't going to beat Mayweather by using dirty tactics.