My fitness pet peeves are actually very few I think. One of them is waiting for a specific machine. Usually my programs are varied enough that I can move to something else and come back to that exercise a bit later in order to get it all done, but it annoys me. That type of thing especially annoys me when the gym is filled with college kids that really aren’t doing anything except posing and trying to look good for the girls there or something. I think the chicks would be more impressed if they actually saw the guys doing something rather than sitting on the bench press bench looking around.
That brings be to working out in a group or alone. The fewer people in the gym the better! I can get to my things easier and get my workout done faster if there are fewer people there. As for classes I tend not to do them simply because of how I choose to spend my time at the gym. When I have done classes I tend to get a bit bored and distracted. Working out on my own definitely works better for me.