We spec writers are constantly reminded to avoid On The Nose dialog. The best way to do that is to read exceptional scripts that have exceptional dialog. I'm currently reading 'On the Basis of Sex' by Daniel Stiepleman. On Page 46 is an example of dialog that could well have been reduced to classic OTN but the writer demonstrated his skill. The protagonist, lawyer Ruth Bader, had to struggle in her early years in a male dominated profession. Now, years later and a fierce advocate for equal rights and combatting all forms of discrimination, she has taken up a cause initially promoted by her husband Martin. In New York, she's about to catch a taxi to the airport to fly to Denver to meet the plaintiff, denied tax assistance from the Fed Govt to act as carer of his aged mother - on the basis that only women are considered eligible for this role and consequently eligible for assistance. Point being, the plaintiff is a 60 year old male, Charles Moritz. As the taxi pulls away, her young son James asks of his father:
JAMES
Daddy. Why's mommy going to Denver?
MARTIN
She's climbing a mountain.
This dialog blew me away and my suspicions, on first beginning to read, that this was going to be a great script were justified.
Imagine what a lesser writer might have written.