Is it rude? (Group Fitness)

Do most group fitness instructors find it rude when participants leave class early?

I was a culprit this past weekend. I went to a spin class, and literally, within 5 minutes, I decided that I did not feel like doing any cardio, so I got up and left. Now, there was nothing wrong with this particular instructor. I have taken his class a few times, and he is definitely above average, but didn’t feel like I had it in me to do cardio and strength training.

With other instructors who I do not like, I usually just leave when I see they are teaching, and try to be as inconspicuous as possible, before the class starts. Occasionally, (and this is probably the worst thing to do) I decide to give someone whose class I do not like that much another chance. Invariably, after 15 minutes of a frustratingly annoying workout (for me, in any case), I up and leave.

If I were an instructor, I would probably think this is pretty rude. 1) It could be a distraction to the instructor, who might then become more self conscious of his/her own performance. Then again, maybe it is their job to deal with this sort of thing. 2) It definitely is a distraction for other people; it takes away from the rhythm and energy of the class. I have gotten to points in a class where I see someone leave early, and that makes me lose a little bit of motivation. It is for this latter reason that when I go to a 2 hour spin class, the instructor makes us commit to either a normal 45 minutes, or else the full 2 hours. Imagine starting to fight after about an hour and a half of intense spinning, and then people start getting off their bikes with just a little bit left of the class to go.

I would be curious to know what most fitness instructors think about this. Do you hate these early leavers? Do you even notice when this happens?