There is such a thing as hyperbole. Learn it, use it, love it.
Basically, I've seen most portable audio devices simply don't have the kind of hardware to produce accurate samples without lots of local interference, timing inaccuracies, and delayed channel crossover. Joint stereo is one thing, hearing a time-delayed, faint copy of the left channel on the right speaker is another... Yes, I can hear that.
Secondly, I have yet to see any portable device that can drive a set of good high impedance headphones. They simply don't have enough power. And in order to actually hear the lower frequencies (which require LOTS of power output), it would require a pre-amp... Which essentially throws portability out the window.
So, yeah. I don't much like MP3 players because of the nature of lower quality and power in portable devices. Simple as that.
Call me spoiled, I guess.