I've become a much nicer person lately, and when I see people do it I just don't say anything anymore. I grouped with a WHM that insisted he was always out of the red crap, but as a bard I could clearly tell he didn't even TRY to move until it was way too late.
Then again, I've been guilty of it as well (mostly due to not knowing fight mechanics). In fact, you yelled at me quite a bit last weekend doing those Garuda runs. "Damnit Gravel, get out of the purple shit!" The entire time I was saying to myself...what purple shit?!