Dialogues: Sherlock's character

Is Sherlock really an autist or does he choose to stay away from "normal people"?
He is often absent-minded, slightly depressed -bored.
In the serie, that gives an opportunity for funny dialogues:
Sherlock - John - 

1.2. The blind banker / John arrives at Baker Street. 
- I said could you pass me a pen.
- When?
- About one hour ago.
- You didn't see I was out, then.

Later at Baker Street. Watson has been arrested by mistake instead of one of Sherlock's informer:

–  You've been long.

–  You know how it is. Police don't like to be hurried, do they. Formalities. Fingerprints. Charge sheet. I gonna be convened in Court on Tuesday.

– What?

–  Me, Sherlock, in Court on Tuesday. They're giving me an ASBO!

–  Good, excellent.

–  Your little pal can go and give himself up when he wants...

–  (looking at a picture) This signs puzzle me.

2.1. A scandal in Belgravia / At Baker Street:

- We agreed!

- When did we agree?

- Yesterday

- I wasn't at home yesterday, I was in Dublin.

- It's hardly my fault if you weren't listening.

3.3. His last vow / In a taxi: 
- We did discuss it.

- People were talking, none of them me, I must have filtered

- I noticed

- Had to filter a load of witless babble. I've had Mrs Hudson on semi-permanent mute.