Most of my tracks are ill at some point...
And many of them stay that way. Heh.
One thing that helps me tremendously in trying to make my tunes as healthy as possible is "round robin" mixing.
I go through and mute everything... then I pick out pairs of tracks, and listen to them together. Sometimes when I listen to a whole mix, I don't here the interplay very well -- spots where the kick drum rhythm and the bass don't fit very well, or where melodies (especially counterpoint) and overall harmony are a bit too dissonant.
I find this is also a very good way to evaluate takes for timing... If I'm comping vocals, say, I'll just listen to them against the drums + bass. Guitars, keys, whatever else often just get in the way of hearing what's important.
Maybe this is mixing 101, and everyone does this...
-Garret