Q: How can I tell if a guy is into role playing?

Answer:

The only way to really find this out is to ask unless he has already said one way or the other. Although some guys may deny being into the idea 

but secretly like the idea because they may feel embarrassed of the fact. The problem here is if you try to force the issue it will likely make them uncomfortable so it is a difficult situation. Typically if the guy says no it is best to accept the answer. Things may or may not change over time as he becomes more comfortable in the relationship but never count on them changing.