This. Why the hell do people do that? The problem is that it sounds fine on my computer speakers so I never know until I actually listen to said songs on my iPod.
You could find entire articles about this very phenomenon. What has happened is that music producers are turning up everything in the mix to max levels. Modern production doesn't really allow anything to breathe. It's been done to give the illusion of more bass and feel, with the intention of keeping the music from sounding "tinny" on crappy computer speakers or ipods. The end result is a loud mess that's very grating after a couple of minutes. It's a real problem, and it's one of the reasons that vinyl is starting to make a minor comeback among non-audiophiles.
The new Metallica is quite guilty of this. But the problem songs I'm talking about are comically loud. Turning it down to minimum volume and still hearing it loud. I understand the new production thing but at least those songs don't scare the shit out of me when they come on randomly unlike the ones I described.