What is an Unfair Question?

A question lacking content, asked only to embarrass or disconcert a witness, i.e., A question not in accord with an attorney's professional standards.

Lawyer's Tricks or Chicanery
Actions used to surprise, deceive or outwit a witness E.g., Asking "rapid-fire" questions, subterfuge, etc.

How do lawyers use subterfuge?
Two common examples are:

Misquoting the witness or a written document and asking the witness to agree with the incorrect assertion, and
Claiming support from a nonexistent authority,
E.g., Dr. John smith has reviewed your report and has stated that your opinion is totally wrong, how do expect the jury to believe you now?
Answer: May I see a copy of Dr. Smith's report (or the document to which you refer) so I can respond to his comments?