I always think it's funny when players after a tennis match will wipe their hair or forehead which

[a kennedy]

is all sweaty, then shake their opponents hand. Ick.......

[brush]

1. Both players are sweaty after a tennis match.

I doubt either player gives it a second's worth of thought.

[BlueTsunami2018]

2. Try playing contact sports.

Or going in a mosh pit.

You’re wearing everyone’s sweat, blood, snot, spit etc..

[hlthe2b]

3. Knowing they are headed for an "after-match" shower, I doubt it concerns them much.