Dirty talk and role playing are different things.
To get sexual pleasure, a lot of things needs to be there. Beside vanila sex, couple has to introduce foreplay, change of position, add fantasy, dirty talk, role play, all these are good for spice up sex life.
You are asking two things, dirty talk and role play. On dirty talk, a lot of couple like that, a lot donot. My experience is, mostly girl like harmless dirty talk, not hardcore one. Few didnot like at all, only a few loved hardcore talk. Whatever you do, make sure that remains within the room, once sex is over, curtain open, dont try to reconcile why who said what. Leave the talk there. Think about next session.
On role play, the rule is create a situation, and dont cross four walls. Everything starts there, ends there. A lousy use of word might be fatal if the other remembers and keep chanting later. Like you talk about her mother or she talk about your father on the bed. The other should never discuss on that.
You are with a girl friend and if future is together, you are exhausting all your arsenal of spice up sex life now. What is your plan for future?