Midlife,
I started to do a couple of paragraphs re theories, but decided since
some things are contradictory (there are pairings that work as a
contrast, though more often one probably goes for complement), it would
be too confusing in an FAQ. Even some of the basics - using acidity to
cut through fattiness- have counterexamples. I'm sure there are sites
that discuss this in detail, if you find them please let us know. I
thought of trying to google this group for some of Ian's posts, but
found more specifics than theory.