A note on editing dialogue:

This really just dawned on me. It is something I have been doing for some time as a writer, but I only really just identified how I was using it. Hopefully it will be of some use to some one out there.

I tend to put as much as I can on the page in a first draft - often its not enough in some places, but mostly it is overwriting and I wouldn't have it any other way. From there I scale back. It happens in stages, but there is no point at which the stages are mutually exclusive. If something needs doing and I recognize it, I almost always do it in the moment (unless it is a distraction from a bigger task.) First I look for wording that is unclear and or unnecessarily complex. Sometimes there is a purpose for convoluted wording, but usually I was wrong in the first pass. Next I strip away most of the conversational dross. I write SO many sentences that start with "well", "but", "yeah" or "okay" almost none of which adds to the core ideas or character voice, and almost every single one of those sentences work better simply by clipping that opening verbal detritus. Repetition also gets a good scrubbing at this point too.
Doing these surface-level changes first means that I read the script a few extra times (Usually I read it at least once without making a change before any of this.) to re-familiarize myself with the details as much as possible.
Once these first changes are done things get more complicated and much more tailored to the specifics of the writing - the theme, the plot, the characters. An element of this is what I had a realization about.

I'm going to use my actual dialogue to demonstrate:

A: I refuse to be seen as someone who would condemn millions of people to death.

B: If it came to that, your self-image would be moot.

(That first line is actually the last sentence of a longer passage, but it is all that is immediately relevant.)

My first pass - the really surface stuff - resulted in the first line being scaled down to:

A: I refuse to be seen as someone who would condemn millions to death.

B: If it came to that, your self-image would be moot.

The "people" is pretty clearly implied - especially with the context of the preceding dialogue (you can take my word on that.)

My next pass...

A: I refuse for that to be seen as my legacy.

B: If it came to that, your self-image would be moot.

Much shorter, and again we know from context what 'A' means.

The next version is where I really had my epiphany.

A: That will not be my legacy.

B: If it came to that, your self-image would be moot.

Half the length of the original sentence, and 'A' doesn't hint at it being a matter of how they will be seen by the world. Because 'B' says it all. This changes 'B' in big ways. Instead of simply reacting and cutting 'A' for being worried about how 'A' will be perceived, 'B' actually does some mental work and reads right through to the sub-text of what 'A' says and in the end accomplishes all that was intellectually there before and more.
In the final tally this: 1) makes it more entertaining dialogue, 2) is more concise, 3) does more interesting things with both characters, 4) Doesn't pander to the audience!

As is so often the case, less is more.

Like I said, I've been doing this kind of edit for quite some time, I just hadn't quantified it and thereby realized what I was doing.

Good luck!

MVP

This one makes me howl.  It was probably funnier ten years ago when the references were that much fresher.  I didn't write this for any reason but to amuse myself... that happens a lot.

EXT. OUTSIDE MADISON SQUARE GARDENS, NEW YORK - TWILIGHT

Broadway is barren of people.  The sky is a dark, dirty red.  There are huge potholes in the pavement.  Abandoned cars litter the street.  Windows in the surrounding street are long since broken.  Vines and creepers cover many things.  It has been a long time since this place was disturbed by sentient life.

Madison Square Gardens itself is in terrible repair.  The roof appears to be caved in and the doors are broken off, hanging on their hinges.

A lonely wind blows dust down the street.

The sound of horse hooves echoes between buildings.

A pair of horses appear at a trot.  They slow down to a walk outside of MSG.  Atop one horse is an earthy, busty, beautiful woman in a short buck-shin dress.  On the other - Brendan Shannahan.  Shannahan is dirty and unkempt.  He is wearing a loin cloth.

He dismounts and helps the woman down.  He looks at MSG in awe.  The couple enter the colesieum.

INT. MADISON SQUARE GARDENS, RINK LEVEL VOMITORIUM - MINUTES LATER

Dim light fingers through the huge hole in the ceiling.  Rubble is strewn across the rink and the seats are all in dis-repair.

A lonely zamboni, broken, sits mid-rink.

Through the passageway enters Shannahan and his female side-kick.  He enters the rink area and looks around, gaping in disbelieving horror.

He casts his gaze upwards where his eye falls upon a banner in the Rangers' colours.  Boldly printed on the banner - which hangs askew from a broken girder - is the number "99."

Shannahan falls to his knees and pounds the floor.

                SHANNAHAN
     You did it.  you finally did it you bastards!  Damnit all to hell.  You blew it up, you bastards.  God damn it, you blew it up!

                VOICE OVER
     Well, let's not get ahead of ourselves.

                                                             SMASH CUT TO:

INT. HOCKEY RINK - MODERN DAY

A chimpanzee stick-handles down the ice....   Skates in on goal.

He shoots!  He.....