Many people find it hard to suspend disbelief. In training for acting at ren-faires a lot of work goes into this - both for the actors themselves and to teach them how to extend that suspension to the patrons with whom they will be interacting.One of the interesting things about working ren-faire is observing the different levels of suspension of disbelief that people operate from.
(from which people operate. that participle is actually dangling - it's suspended from my disbelief)