Yeah - this is something I've moaning on about just recently. My Mission speakers are very bright - they sound very 'forward' and accentuate the highest frequencies with a nasty edge to vocals and sharper sounds.
This is also something that can feed through from other components from CD players to amplifiers - even wiring and the nature of the original recording can cause this, I've found. Most unpleasant in the long term!!.
Edgy, shrill, grainy. All of these are elements of bright speakers. Music does not flow effortlessly, but instead sounds somehow artificial and forced. Listening to music for long periods is both fatiguing and even unpleasant.