Personally, I dislike 2 things about most tanks:

1) Waiting forever to pull mobs (i.e., they aren't waiting for buffs, they are just standing around for no apparent reason)
2) Taking wild amounts of damage due to poor cooldown management, poor gear optimization, not moving out of AoEs, whatever.
3) Ok, 3 things: Not holding threat. Come on, guy. Use more Flash/Overpower.

People who hate tanks for not taking the most optimum path are a little too finicky. Personally, in DF, I'd like to see:

a) Someone not level 50? Hey, this is an xp run. Pull it all.
b) Everything level 50? Let's hurry it up, ok?

I kind of hate going into dungeons with myself being anything other than the tank, just because I hate having to deal with the nonsense that comes with most tanks. If the tank is not wasting time unnecessarily and is actually tanking, people should just get over it if the tank doesn't pull the dungeon the "absolute best way". Be happy it's not as awful as it usually is.