Dark and laid back vs bright and forward

What do reviewers mean when they describe an amp as dark? Laid back? Forward? Bright?
Many of these terms are difficult to understand without having some 'authority' providing precise definitions. Robert Harley attempted to present a little clarity in his book; "The Complete Guide to Highend Audio." I know a lot of people don't really care about what a paid reviewer thinks or says, and some people will reject his definitions out of hand due to the source, but it seems like it would be helpful to have just one definition for each word. Now if we could just settle on a source!
Is there any other colours of sound?
Any Red Green Blue or combination of three?

I guess the best reference on that issue could be Miles Davis' "Aura" album with all colours of rainbow played with trumpet. I assume that colour in MUSIC can be specified with certain tone for example G for green, G# for bright-green and G-flat for dim-green... Still don't know what tones are used by Miles in that Album. Should definitely check.

Should you ever figure out Miles Davis please clue the rest of us in. One hundred years from now his music will still be cutting edge.

Loved your expaination of dark and light sides of reproduction. Maybe there's a Star Wars connection there. You know, maybe tubes are using the light side of the force and s/s the dark side. At any rate, may the force be with all of us.
It is not possilbe to reproduce a live musical performance exactly as performed in the auditorium or studio in your living room.

However, getting as close as possible to 'true to the original' is the only valid goal for the audiophile --the 'connoisseurs of coloration' reviewers (who obviously get paid by the word) notwithstanding.

The first priority to achice this goal is speaker selection appropriate to a specific listening room. Then their set-up and the sonic quality of the source material. Followed by the support components best suited to those speakers. Cables and tweaks following suit.

So, I substitute 'real', 'accurate', or 'neutral'. for the terms 'bright', and 'warm', etc., for describing degrees of 'distortion' or 'coloration'.

I also recommend trusting your own ears. Recall 'live' sounds you have heard, and compare what you hear in your system. The more dramatic is in the low frequencies. The 'boom' of a 'boom-box' makes a low frequeny sound that no known musical instrument is known for making, for instance.

The 'bass' sounds should be identifiable as the bass guitarist playing in the lower octives (which he does not always do, by the way), each pluck of a string individually identifiable, or the kick of the bass drum, short and snappy (like real), etc.

Beware the 'psycho-acoustic' phenomenon. When the telepone first came out people were quoted as saying. 'it sounds just like talking in person'. Of course the telephone is not there even yet. Shakespear wrote, 'to thine own self be true', indicating how long self-delusion has been going on in human thinking (perceiving).

When I tweak my system, or nudge the speakers a bit, and then listen (a bit harder) for a difference, it always sounds better (not just different). Of course it is no doubt the result of 'listening harder' and the tweak made no audible change at all, good or bad.

Anyway, if you have trouble remembering 'real' sounds, start listening. You will be amazed how well you can do on your own --without just resorting to the eloquent terminology of the 'connoiseurs of coloration'.
OOPS! I realy forgot to define a worm sound!

Here it goes:

A real worm sound is usually heard through larger than 100W/ch class A amplifier when on the listening distance you feel that wormth.

Not intend to blame class A amplifiers rather than just bringing definitions to reality, folks. I adore Plinius poweramps but damn, it's a hot summer comming right now!