I totally agree with this. I'd like to add: be prepared and ready to go soon. Don't be the guy who has 24 other people wait because they really want to finish that AV

This is a very gray area; while it is important to stick with a group and help new players learn content, it is also important to know when you are wasting your time.

For example, wiping twice during jousting in ToC because you've never done it before is fine, it's a unique encounter for a fresh 80. However, multiple wipes on trash pulls in a heroic require a reassessment of the group.

When to leave and how to leave politely are both very difficult calls to make and execute gracefully.

Perhaps there should be a debuff similar to Deserter for folks who bail on a PUG.

I, too, am frustrated by having to spend an hour or two looking for a fifth member only to see the group knocked back down to four or even three after the first wipe. Back in his pre-nerf days, I must have made 10 unsuccessful runs against Skadi just to get to the Elder on the other side of his locked gate, yet these runs occurred with probably five different groups because folks kept dropping out each time we wiped. And no, I never did get the "Elder" title, and it was entirely because of him.

And then there were the Direbrew jerks I had to deal with just to complete Brewmaster. This was a trio of self-admitted 12 year-olds who invited folks into their PUG only if they still had a summon, and once it was used suddenly Master Looter was activated, denying the unsuspecting sap any drops. The moment Direbrew was dead they were kicked from the group and replaced by another sap.

And you wonder why I wish Blizzard would let us hire NPC mercenaries that we can take into instances.

Sometimes you need to know when to bail. Today I pugged ony10 with a group mostly consisting of players from the 2nd best hordeside guild on my server and yet we wiped 3 times due to tailswipes and a sleeping offtank. When your group is bad enough that their gear cant carry them to ony10 then it's time to bubble hearth. Which I chose to do while main tanking ony on our third wipe.