Here is a thread for logging bugs with certain quests. Just so the BUGS thread doesn't get blown away with content.

Mulgore:
- "The Ravaged Caravan" = There are missing crates by the caravan so you can't open everything and complete the quest.
- "Dwarven Diggers" = None of the dwarves drop mining picks.

Barrens:
- Hunk of Meat Delivery Quest - As soon as you get it is marked as completed.
- Leather Bundles Delivery - Same as above. You have to take the leathers to thunder bluff but the guy that you have to talk to doesn't light up with the "?" so you can't talk to him about the quest.

*** update Feb 25 ***
Barrens:
- "Lost In Battle" - you have to find the doods dead wifes corpse. Well I found her but she is alive, supposed to be dead. Can't complete the quest.

I know on the pay servers delivery quests are marked complete as soon as you receive them.  This is so when you find the recipient, you just "Complete Quest" and get your reward.  But if there's no "?" above his head, then that's a problem.

"Boulderslide Ravine" - You have to kill Kobolds to collect 10 resonite crystals. Well one, the enemies there are not called Kobolds, they something else ("Grogger"?) and two once I got there I collected 9 crystals then they stopped dropping them. So I couldn't get the tenth one to finish the quest.

"Jin'Zil's Forest Magic" = You get this quest in stonetalon mountains. You have to collect a bunch of stuff, one thing is a Fey Dragon Scale. Anyways whenever I go to attack a "Wil Fey Dragon" it kills me instantly (literally). Whats up with that. So I can't complete the quest cause I can't kill a fey dragon to get its scale.

I find at least 50% of the quests where you have to collect things, ie 5 moonstlaker pelts, or 10 cave crystals or whatever, end up not being completable.  Which, can be annoying.

I have yet to experience that.. but I am way lower level than you Hawkeye.
Do you just have to abandon these quests or do you eventually get the item required?

"Warsong Supplies" - Given to you at Silvertree Post in Ashenvale. You have to collect a bunch of things and go all over the place to get them. One of the items the "box of axes" you have to go to Booty Bay and get it from the wharfmaster. Well I got there and the dood didn't have a question mark over his head so I couldn't talk to him. Meaning I couldn't get the box of axes.

"samophlange" - Given to you in Ratchet. You have to shut off a venture co machine by turning off three valves, the first two turn off the third one you can't.

K pretty much every quest that requires you to put an item on SOMETHING in the world doesn't work. Either the something is not there (where it should be) or when you put the something on the object (if it even lets you) nothing happens.

All the quests where you have to follow someone or gaurd someone you can complete right away. That someone never moves... ha. So those ones are easy!

The "Ravaged Caravan" mission still can not be completed.  No crates to open.

The Cleansing of the Wells missions can be done without actually going to the wells.  (But you do have to collect the animals parts to make the totems)

I've notice some missions give you the chance to complete it multiple times, at the SAME time.  I did that with one mission and quickly got 7K in xp.

Yah I've noticed that one too. Every quest where you need to protect people you can complete right away. I was in Desolace (as another example) and two quests I picked up right away one as a bodygurad for a little goblin and the other for escorting thier caravan. Well the caravan was spawned all along the road right to the point where you are supposed to finish.

As soon as I picked up the quest I just went over to the guy that gave me my reward and I was done both of them... easy. ha.