Do you truely know how to Know a player

I think its important that ppl know how to truely know if your opponent is a fish or lion.
First i like to watch how they play pre flop the flop and turn. Not necessarily What Hand MY opponent shows but how he went about playing it. Lotta players calling DONK!!! when they lose to a q 9 suited player sitting on the button, calls a 2.2x bb and flops a draw. I dont think i should give anything away cause i learned the hard way and i thikn yall should too! No one paying me for coaching lol. Point is how many of yall really know how to Pin point a pro or a fish???