Sorry SemperJase,
But there is a whole big enough to drive a truck though in the logic that you are proposing.
I'll give you an example.
Let's say I'm cast in the part of a villian at a reniassance festival. I'm not getting paid for it, but what the heck. It's kind of like community theater.
They want me to really play it over the top. They want me to play a voilent, corrupt, lustful, inpious priest. A powerful one at that.
So, I go ahead with it. I have fun with the character. I torment peasants and give viled threats. I reward my underlings for thier devious natures. When audiance members insinuate that I might even participate in nasty things with alter boys, I coyly skirt the issue. I even go so far and try and entice audiance members to be just a cruel and debauced like me.
And all the while, the audiance keeps asking for more.
Am I morally wrong?
Am I evil?
After all, I am role playing in the strictest sense of the word.
Am I polluting myself because I an putting forth a fictional persona who is corrupt?
Think about this, because you should realize that you can't have light with out darkness.
You can't have a virtuous hero if they is not some villian to overcome.