lol. That's too funny, man. You've totally got a large portion of this board's completely-cryptic-thus-unhelpful-to-beginners approach to advice pegged. (They're usually right when they say shit like this, btw - but I totally understand what you're saying - there was a time for everybody when we didn't understand why "you just can't fix it in the mix" and other vague things of the sort. Hearing them a thousand times didn't help anybody learn why, though - helpful little tidbits of advice that are actually
usable helps you get there a little bit at a time.
So here is one of those useful (for me, at least...) tidbits:
The two most important mix-time effects are EQ and compression. Traditional wisdom (and many, many manuals that came with hardware compression units, EQs and mixing boards) has always said to put the compressor first, and then the EQ, so that the EQ does not alter the
tone-related effects of the compression. This traditional wisdom may have been completely practical before the "wall of sound" thing caught on, but the problem today is: EQ after compression alters, and in some cases can largely undo, the actual
dynamics-compression effect of the previously-applied compression. For this reason, I have found it to be infinitely faster in a "wall of sound" (aka:"typical modern commercial sounding" - whether you love 'em or hate 'em...people pay for, and expect 'em) mix, to put the EQ before the compressor, so that after I do the initial parametric sweeps and notch out the nasties, if any exist, I can smash the track into shape, and then EQ out any nastiness which appeared/surfaced as a result of the compression, without the vocal (or whatever) becoming undesirably dynamic as a result of the EQ applied, which would then necessitate another round of compression, which might impart or reveal yet another unpleasant sound on the track, which would require more EQ, then more compression etc. etc. etc. Either way you're gonna go back and forth (to some extent) adjusting the EQ and compression side-by-side until you find the right balance that gives you a non-dynamic, nasty-resonance-free track, but I have found that putting the EQ before the compressor gets the job done much, much more quickly.
Works well for me, you can hear a few mixes I've done on my myspace page (which is linked to somewhere on my profile here on this board).