When it comes to expressing your view and your mind is in dilemma, then you can't be 100% right about what you are saying and conclude something by saying something which leads to two different paths. That's when we say there is a grey area and that's how a single color is defined.
In general when we talk about our opinion when we are diplomating and there you find grey is but when you are transparent about your thought process, things can be either black or white.
It's not a good practice to keep anyone in dark about your hidden intention because that ultimately leads to disappointment. It's also good to be clear about what you think and what you say, it may sound very blunt but that bluntness for while is good rather than keeping someone in dark.
People often change their color and don't stick to one, I believe people with high moral values stick to only one color and be transparent about what they think.
