If she can say "Oooh daddy, I love it when you do that!"
That's dirty enough for me.  

Good topic though - I imagine it's somewhat ymmv.  The girl has to be open to it and know that you are into it.  I've found that many girls are open to it with some encouragement.  Start off slow and gauge her reaction.  If you come out of the gate swearing like a sailor and expect it to be foreplay for her - it may not go so well.

I used to know a girl that could dirty talk so well and sincerely she made me blush.  Which is not easy to do.   I'll steal a line from A Christmas Story-

(S)he worked in profanity the way other artists might work in oils or clay. It was (her) true medium.  

Lol

...to me, there are no limits or boundaries and I love to do the same but you have to use me like you own me while doing so and make me beg for more, please.....
Suzee