What exactly is colored sound?

I guess the definition would be a deviation from what what was originally intended but how do we really know what was originally intended anyway?  I mean solid state mostly sounds like solid state.  I guess that would be a coloration, push pull amps and set have their own colorations.  It seems we try to denote certain definitions to either promote or dis certain sounds I guess.  We could have a supposedly neutral amp but their just is not enough bass so we turn up the subwoofer or the bass, a coloration per se.  I guess one could say that colored sound would be a good thing.  after all, each instrument has its own sound (color).  A mullard, a telefunken, I mean who knows what tubes were in the recording studios at the time of the recording.  Syrupy, sweet, rich, NEUTRAL, forward, backward I mean really...  I guess its all about certain preferences for each person.  even in the studio.  who knows, maybe a recording may be meant to sound syrupy or sweet and then we try to make it as neutral as possible.  Maybe thats a coloration in itself.  I guess what I am asking is why do reviewers use the word colored in reviews anyway?