I was at the local courts today, watching mostly 4.0 and some 3.5's play doubles and singles, 4 courts being watched.
The only guy who had a somewhat decent form serve was a 4.0 who just turned 70. He doesn't hit it hard (well, he's 70 !), but at least he turns fully sideways, get's the racket to trophy position, archer's bow, and hits upwards at the ball.
The other 10 guys all had some weirdo hitch you never see in 5.5's, much less pro level tennis, most pattycake their second serves, some have no clue whatsoever, some pound both serves the same (and miss the second).
These are supposed to be my peers.
No, I haven't talked to every one of those guys. The 70 year old and two other's know my serve, think it's with good form, and I hit much harder first serves, and much more spin and pace second serves than anyone there.
My movement sucks, and I hit stupid shots all the time, of course.
Seems 10 out of 13 players on the courts could use some basic serve instruction, not that it would really help their overall game.