Elementary, Season 1

Watson:
How do you do it?

Holmes:
Do what?

Watson:
Guess things.

Holmes:
I don't guess. I observe and once I've observed, I deduce.

Watson:
You said you could tell from my hands that I used to be a surgeon.

Holmes:
Hand singular, actually. It was soft, no callouses. Also, it smelled faintly of beeswax. Many surgeons, as you know, use beeswax cream to protect their hands from dehydration after repeated washings. Old habits die hard. I don't see why you gave up your medical career to become a companion. I'd wager that addiction claimed the life of someone close to you, and his or her death led you to make drastic changes in your life. Am I close?

Watson:
What about my father?

Holmes:
What about him?

Watson:
How did you know he had an affair?

Holmes:
Google. Not everything is deducible.