Not having played a Hunter at that point, I had a fuzzy notion that Disengage somehow reduced threat and was highly affronted at any hunter with aggro spikes who wasn't using Feign Death over and over again. After starting to level a hunter alt, it quickly became apparent that: a). Disengage was a melee-only skill that still had to "hit" the mob, and b). Feign Death wasn't exactly a spammable ability and could be resisted no matter what you did. I am by no means an expert hunter player, but I have at least learned to bellow, "FEIGN DEATH ON COOLDOWN!" if they're not trapping (and just minding my own business if they are).
I am still occasionally reminded of my days as a backseat hunter, and never more so than while listening to my GM trying to figure out what's gone wrong in a raid.
Despite being an extremely organized raid leader with chart-topping dps, he's never played a healer. Virtually every night we dragged ourselves through SSC he could be heard asking, genuinely baffled, "Why do our priests have so little health?"* or "Why did (dps running around at a distance requiring binoculars to see) die on that last attempt?"** The issue keeps popping back up, especially on any healing-intensive fight that requires us to spread out as much as possible (Gruul), split the number of healers covering multiple tanks (Maulgar, Karathress, Illidari Council), or when the raid-wide damage is so bad (Vashj, Naj'entus) that it's virtually impossible to ensure that lower-health dps can be kept comfortably topped at all times.
Unless you've played a healer, it's not necessarily obvious how much the job is dependent on the ability of individual players to avoid unnecessary damage. Someone who moves during Flame Wreath on Aran, or too many people clumping together for Gruul's Shatter, or a tank who misses a few blocks, are probably going to make you blow through a ton of mana trying to keep them up. But when you're learning a fight these things are just going to happen, and you know perfectly well that sometimes you're going to have a choice over which question is going to be asked at the end of the attempt: "How did the dps die?" vs. "How did the tank die?"
I hear about this a lot from both tanks and healers trying to keep their 5-mans alive, dps with CC or kiting responsibilities, and from raiding friends elsewhere whose hybrid class leaders haven't necessarily played more than one spec much. While it's somewhat related to how popular any given class is - fewer assumptions are made about, say, Warrior abilities than their Shaman counterparts - it's still the rare person who's leveled every class to 70 or even played all the specs on their toon as a regular habit.
The requests made to Poly a bleeding mob, drop back-to-back Fire Elementals for trash fights, or Sap the un-Sappable keep coming. With WoW going on its second expansion, are you still running across players who expect the impossible?
*Unfortunately the Primal Mooncloth set has no stamina unless you gem for it
**"Because they ran out of range when they got aggro!"