Your yardstick of "good group behavior" could use some adjustment.
Derping just for the lulz should be saved for runs with friends. If you're in a pug group, it's better to have a little more courtesy and professionalism.
Honestly, I usually don't do any of those, maybe like once in 10 FPs or so. I just wanted to point out that it's no big deal (at least to me). lvl 50 FPs are like carving a cake for lvl 55 group anyway. They would probably do it faster using their basic attacks than lvl 50 group taking the whole thing seriously.