Be clear that when you drop in to a class here you are an interloper. Do not expect the instructor to make any accomodations to your needs. For example, if you find the cut-rate muzak played in the class to be at too high a volume, then if you ask that it be lowered, you will be told " Oh yes, I play my music very loud. Some like it, some hate it." Get over it, stranger, is the subtext.