Federal prosecutors want Barry Bonds to go to Prison. They are seeking a sentence of 15 months for the former San Francisco Giants star. The charges stem from his obstruction of their investigation into BALCO, steroids, human growth hormone and other performance enhancing substances and their illegal sale and distribution to professional athletes.
The most common reason for a nose "itch" is not a rash, a nasal hair or allergic rhinitis - it's anxiety. This is also true for similar sensations elsewhere on the face and neck. There are many reasons for anxiety however, and deception is but one - but it's a very common one. Depending on the particular area touched/rubbed/itched/etc., the other nonverbals it is clustered with, the paralanguage and the statement analysis/language analysis - if you know what to look for, your ability to detect lies is very significantly enhanced.
Everyone tells "white lies". The next time you tell one, or even think about telling one - if you're self-aware (everyone thinks they are - but this is true for very few) - you'll notice that somewhere on your face or neck will probably itch. You may be like Barry Bonds or Megan Fox (See Lie Detection Secret # 652: Megan Fox has got an Itch) and scratch your nose, you may be like Jon Corzine (See Negotiation Body Language Secret # 339: When a Lie is Heard or Told) and scratch next to your ear. It can even work in reverse, for if you hear or see something you believe to be deception, as Angela Merkel does here (see Negotiation Secret # 29: Eye Rub when some else is speaking - Angela doubts Vladimir) - you'll have similar sensations and may rub your eye like the German Chancellor.
Remember, there is no one body language signal for detecting a lie. Many things must be taken into account (see above) - including the honest person who experiences anxiety associated with being falsely accused. Paul Ekman calls this the "Othello error" after the character in the Shakespeare play of the same name, who falsely reads his wife's (Desdemona) signs of anxiety as that of guilt.