I do not Nano blitz. Ever. I will gladly play anyone who wants to play because I enjoy playing a fun, clean game. If I do blitz, it is always a legitimate blitz.
Also, people use the word "Nano blitz" to mean any blitz that has a rusher come free. if you blitz six people and one comes free from the outside, that is not a Nano. That is just simple math.
A "Nano blitz" is technically any blitz that send the pressure up the middle. It is frowned upon in NCAA (including by me) because almost all Nano blitzes in video games are the result of a glitch where a linemen comes unblocked.