Well, it's not considered being a dirty fighter, just getting by however you can.
I mean, if they wanted it to be completely fair, they would make it like Mortal Kombat, and you both start out..and are ready. I would'nt like it like that.(don't get me wrong though, mortal kombat is really awesome, but this is an adventure game..not really a fighting game)

Like someone mentioned in here, he is just getting better/smarter with his fighting skills. I think it's really awesome the way they are adding that.
In my opinion, it would'nt be considered a dirty fighter.