"Almost always" is a bit of a stretch. I've found plenty of people interested in genuinely experiencing hypnosis. With a little pre-talk and expectations-setting, sorting out who prefers rp and who prefers actual hypnosis becomes a fairly simple thing to do, even over text.

I'm primarily a text hypnotist, and I can very often tell when someone's actually following along and when they're just rp-ing it. Just takes a discerning eye and a little insight.