Hmmm let's see...............
1. Seeing a boom stand set up at a weird angle, like the tilter is the lowest part of the boom arm.
2. Seeing stand tripods extended out as far as they can go. Looks completely ridiculous and is completely unnecessary, not to mention a waste of precious stage space!
3. Seeing countless drummers using no sleeves or felts on a cymbal stand. Like seriously? Those are about the cheapest accessories you can buy.
4. Seeing really high end drums that are tuned like complete garbage and/or muffled to death. Happened last night. The band that followed us, their drummer was using a C&C Club Date Style kit. Looked amazing! He had double ply heads and about 4 moongels on each head. With an Evans EMAD on the bass. Drums sounded like cardboard boxes. If you're going to muffle that heavily so all the tone is gone, might as well save your money and get a used, crappy Excel kit for $50. No one will be able to tell the difference!
By the way, I confess that I am one of "those people" that put RIMS mounts on vintage drums. To me, it's all about the sound. Those clip style and eye bolt (Ludwig) mounts weren't great for resonance. The RIMS mounts help them tremendously. I consider this a "minor offense", because I am not permanently altering the drum in any way (ie no extra holes being added or changing the bearing edge etc.). I can always take it off, put the mount back on the shell and it's back in original condition.