It can be pretty confusing.
I think some of them are a little messed up.
Here's a couple of obvious serves.
From John Mac's serve
1.Second Serve Overview
The side view ---> Kick serve.
2.Second Serve Deuce
Front view-court level-wide.--> Kick serve.
3.First Serve Deuce
Front View wide --> Flat serves.
It can be tough to see what serves they are hitting.
The way I did was, I would open up two different serves, and compare the frame by frame. What their racket face, body position is like at the moment of contact and stuff.
As you will notice, for slice wide serves, their shoulders will open up much sooner than flat serve. On thier kick serve, their shoulders will remail closed longer than flat serve.
I can do this for Sampras's serve as well.
I found it pretty difficult for Pat Rafer to tell. It's just the angle and stuff. Andy Roddick isn't so bad to tell. Sampras's is ok. Agassi swings a little different from the other 3 guys I mentioned. But his serve is most obvious.