Experiences will differ according to the following:
1) An individuals maturity and self control. For example, is there a male student in the class with a history of addiction to porn? Do females in the class think the male model is really cute, and if so, is it a small college in a small community where they'll see the him outside of the classroom? If they start to "come on" to him outside of the classroom, it will affect the classroom environment, usually through eye contact and body language.
2) A teacher's level of professionalism. Unfortunately, some teachers don't care about instilling professionalism in the classroom. The models are on their own, with no support from the teacher.
3) How attractive the models are. If Brad Pitt is modelling, he will get unwanted attention from young females; he won't, in general, have problems with older, mature, restrained women. On the other hand, if Salma Hayek is modelling, she will always get unwanted attention, regardless of the age of the male artists/students. Men, in general, are much more visual than women. At the very least, she will get "checked out" a lot because of her beauty.
4) Where the class is conducted. For example, art galleries with older mature, professional artist, or a classroom full of immature, juvenile students.
5) Some students coming from very conservative backgrounds will have problems from a moral standpoint, really causing emotional stress.