[Hard_Space]

I would argue that for the average person, therefore, 'spectrum' is an unfortunate choice of analogy, since most people believe that it encompasses every possible color. One should not need specialist knowledge to discuss an issue of this kind in common terms.

[Matticus_Rex]

The idea that the word "spectrum" doesn't automatically imply "color" is hardly specialist knowledge, though.

"There's a spectrum between..." is not an uncommon way to describe something where there's a range of possible things.