I've been doing it for some time now. I'll grab a feel of some woman in the street or in the park, then show her a dead spider and tell her it was crawling on her. Sometimes they thank me, sometimes they just walk away.
At first the spiders were just for cover, but now I do it to hear their screams and watch them franticly trash themselves.
Sometimes I'm not sure if they're shrieking like that because they've seen the spider or because I'm pulling off their clothes.