no offence, but thats possibly the daftest thing ever!!!
You take notes on players to record vital info, like the can easily fire all 3 bullets with no hand, or they are prone to spewing, or they are TAG until level 10 then loosen up, that kind of thing.
This is EXTEMELY elpful if you dont use tracking/HUD software, as if you then play these guys again, youll know all this already without trying to remember them.
And if u play on stars or Tilt, theres 200k ppl. Ive probably played the same guy 10 times and not realised.