The problem I have is that 95% of the time when I'm riding, I'm riding by myself, so pointing out every little flaw in the road, hollering "car up!" "Car back!" "Passing!" etc is just not something I'm used to doing. On the other hand, I'm not accustomed to riding 6" off somebody's wheel and hoping they do my thinking for me, either.

I've also noticed among people that do this, a WIDE variation in what gets pointed out.

I'm reminded also of a road in Louisiana where the road sign said "Substandard Road- Next 20 Miles". Maybe that would be the way to handle it on a group ride, since some of the roads I'm on have long areas of substandardosities.