Hey VA - don't start the PA28RRRRRRRRR again!!
It helps if you do know the type. I once gave traffic information on a PA28 and the reply was "yes I can see the Cessna 152".
I checked the strip and asked the oher aircraft who confirmed was a PA28. he was visual with a non squawking not seen primary underneath the Piper! Not exactly mega improtant under a FIS but you catch my drift.
Also becomes important if on an airfield. Ever had "after the landing C182 line up and wait" Could be a little embarrassing if you mis-ident.
Finnally - just knowing the difference between fixed wing and rotary or high wing/low wing would help you. Not least if your instructor says "we are taking the PA28 today" and you go and wait by the C150!!
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"I am not a spotter - just have a healthy professional interest!"