> Would you be fine with going to a class where a significant percentage of people are trying to get you to sell Amway products?

Yes, absolutely. If they are getting in the way of my ability to focus by talking to me about Amway products, then no. Likewise, if they ask after class "Hey, wanna buy some Amway?" and I refuse, that's fine -- one bite of the apple is reasonable. If they keep asking me if I want to buy Amway, then that becomes a problem.

A bunch of people with any ulterior motive in my class are fine with me. Those people not respecting my motives (learning) is the issue.