Okay, here goes! The above terms only apply to solid state amps regardless as to how "properly designed" they are. They are all some thing or the other or a combination throughout the frequency range. However, a truly properly designed tube amp will not be any of those things. It will simply be one or another expression of music. I really think well designed tubes have only musical expressions, no transistors I've listened to ultimately express music.
Dark and laid back vs bright and forward
What do reviewers mean when they describe an amp as dark? Laid back? Forward? Bright?