Keyboard players who play LOUD left-hand basslines when there's a bassist there already HEY YO GET OUTTA MY SONIC SPACE DUDE!!

:scowl:
On a similar note, keyboard players who think THEY can replace every instrument known to man (I'll NEVER forget the day I heard some hotshot declare that guitars and basses will be obsolete real soon, what a DUMBASS!

)
+1 Keyboard players who think they have a particular rhythm element down and don't...
Soundmen who insist on making your bass sound like MUD in the mix! :scowl:
+1 I have an MTD 535. When the soundman got through with it (no names, no location revealed), it sounded like a Precision. DUH!
Instrumentalists with big egos who have a morbid need to play fast technical stuff and be the center of attention ALL THE TIME yet can't play a groove to save their lives or just plain SHUT UP when the music calls for silence.
+1 He who plays the most notes wins!
Showoff instrumentalists who buy and carry around truckloads of THE MOST expensive gear and lots of it only to have it all sound like complete CRAP!
Egocentric Divas/Prima-Donnas and Showoff Melismatic Singers like Sireeeen Dijon, Pariah Scarey, Christina GAGulera and Whitney Houston We Have A Problem,
USELESS IDIOTS ALL OF 'EM!
Uptight/Anal Retentive/Controlling/Micromanaging maniacal people who always try to play God with others.