I did a trial of tests to see how prevailent booting at the first sight of taking greens. Here are my results:
All trials took place in the first part of HoF, as this is the place where the likelyhood of trash greens dropping are the highest (a lot of trash)
I ran this trash 10 times for purposes of the trial (healer = instant queues):
7 out of 10 times someone said something about me needing on the green.
of those 7 times, I was booted 5 times.
The other 5 times I went on to kill the first boss with the LFR group.
So 5 out of 10 times, i was booted from the group for needing on a Green. Seems like the community is rather divided, but personally I see it as 5 out of 10 times, jerks are so worried about a fricken green that they go out of the way to call someone out and get them booted. I also instantly inspected the people who first called me out, and as i suspected, 6 out of the 7 people who first called me out were undergeared baddies wearing pvp gear and greens themselves. Only 1 of them were wearing decent epicd out gear.
Quite frankly this is just amazing. Over a GREEN.