Being a chronic viewer of late night crime shows, I know that yes, hookers canbe raped, and men have been put in jail for doing it. Rape implies being fucked without consent, that could happen to anyone...even a hooker who agreed to give a blow job, but was then attacked.
Happens every damned DAY here in Vegas. Not litterally of course! It does happen. Even in larger cities. Crimes are committed against hookers. Unless it get "Real" the Cops don't pay alot of attention.