Some of these people are cold-readers, who will forever be needing to fix you. So, some degree of skepticism is warranted. Books are oftentimes parroted or undetailed.
But, for those interested in this line of discussion, the aura can be read from your shadow, a personal artifact, signature, or photo.
Your astral or thought body receives and transmits. "Negative" colors can be receptive, rather than evil.
Dull colors can serve down-to-Earth functions, rather than meaning you are intellectually-dull.
I think that talk of money, in spiritual affairs, is usually going to be risqué, but is an outward sign of your belief and investment, in the psychic's moral authority. This being said, there used to be serious, physical consequences, for false prophets. People should not be toyed-with.