Flying around earlier I came across an amazing spot for farming the charms. In jade forest at 44,16 there are these two pillars that summon a stream of instantly respawning mobs 3 at a time.
Just felt the need to share this with everyone.
The instance in Vasj'r works well this year too. You just need to set it on heroic. Method is the same, up to 1k charms an hour. No other loot though.
But it's instanced farming, you won't get any competition there. A pet class can even position and go afk, pet will kill them easily (they only have 9k hit points) Legit botting lol.
There's a ton of good spots in Pandaria, and some of the Cata spots still work. Some of which end up being 1,5k+ Charms per hour as Windwalker or Arcane(my guildie did a really good job stealing my charms ) Skiggit's cave in Valley of the Four Winds is the best in my experience(I feel bad for posting it, but it's on Wowhead anyway)