Jazz musicians (and brass players) generally prefer playing in flat keys (because of transposition making the reading easier) so while "sharp" has a more positive connotation in normal use, if you asked a tenor saxophone player to play something in F# or C# they would generally not be pleased :-)
I didn't think of that. My musical experience is on piano and voice (neither of which has a preference for sharp or flat keys) and I've played around with guitar a bit (which prefers sharp keys in standard tuning) so I tend to forget that some people like flat keys.
