I nearly never alter my behavior for people, forget just girls. 
What you see is what you get. 
I don't alter my behaviour, I just believe that certain things should be kept for different circumstances.
Oh, and where did that post go?
But as for me I do prefer a gentelman, but not one who would act differently to impress me. I would want him to act like he normally did. Even if he was not perfect, nobody is. 
Again, not acting differently to impress. Basically there are times and places for cetain things, bloke talk is something you do with blokes, not girls.