"Not on my watch, you drunken sot!" - When is there too much dialog?

Lea Crowills over at Book Blogs came up with an interesting question. How do you know if you have too much dialog in your novel?

One of the things I've found in writing novels is that dialog is an excellent place to explain parts of the plot without being too obvious. The old adage: "show, don't tell" comes into play here. Of course there are a number of other ways to do that, but dialog is, for me, the quickest. Quite often one of the characters who is new to a situation becomes the foil and asks all the right questions in order to let the other characters articulate or sum up what has happened so far. It's a delicate balance because if you overuse it it becomes obvious that your characters are merely talking heads filling in the exposition and they have no other purpose. That's why it's never a good idea to recap the whole plot in one place but split up the explanations between different scenes. If done right, the reader is not aware of anything jarring about the interchange and does not become mildly homicidal by the time you've got to the end of the conversation.

But dialog can tend to be static, since most of the time it occurs in one situation and while the characters are "talking" they can't be "doing". Or can they? The first time I wrote dialog I used the he said/she said trope like a game of tennis and the characters just stood there having a conversation. Then I learned that you can indicate who's talking by either the type of words that they use or by saying things like:

Christopher downed his glass.
"I'll have another."
The bartender looked at him askance.
"Not on my watch, you drunken sot!"

Or you can simply omit any indication of who's talking because it's obvious from the context.

"What time is it?"
"Are you going to the game?"
"Nope. You?"

But how do you know if you have too much dialog? I'd say there's too much dialog if it doesn't serve any purpose in the plot. If two or more characters are just shooting the breeze, then you'd be as well just shooting the characters too.

But the same goes for action. How do you know if there's too much? If it doesn't move the plot along.

Elmore Leonard, the only living crime writer who's never written a dud, says that the reader perks up when there is dialog. He also says that he tries to leave out the parts of the novel that readers will tend to skip. His novels are packed with dialog, but he still manages to get plenty of action in - but by using short bursts rather than long descriptive narrative pieces. Long descriptions are the parts that readers will tend to skip.

I'd also say that there's too much dialog if you're no good at it. Writing dialog is skill. If you suck at it, people will skip your dialog too.

So by skipping your narrative descriptions and skipping your dialog that leaves... well, nothing really.
So back to the drawing board, I guess.