Let's consider the scenarios:
A) There is a role which has a list of all the colours (and the roles that they have)
B) Scum have a list of all the colours (and the roles that they have)
C) This is a ploy by webadict to spread distrust throughout us all.
If B is true, then claiming our colours is the worst thing we can possibly do. If A is true, it's still bad, but not as bad. If C is true, it doesn't really matter either way. If A is true, then there's likely another role which can determine the colour someone has, but not the role.
Now, our lack of knowledge regarding this can be used by clever mafia very easily. They can try and trick us into thinking that:
A) Our colours mean nothing (if they do; they'll try and get us to claim in an effort to prove their theory while simultaneously getting a list of who has what role )
or
B) Our colours mean something (if they don't, then they'll try and spread misinformation, suggesting that our colours are important/do mean something and anyone who colour claims will immediately appear scummy. Admittedly, alone, there aren't many foreseeable advantages to this, but if there is a role that determines colours, and that role thinks that the colours mean something, then much fun could be had.)
Anyone suggesting that we claim our colours is scummy, Dakarian. I may have been more accurate with my random vote than I thought.
Furthermore, you say that your colour doesn't fit your role; this implies that you have a role which doesn't suit your colour.
Ex: Blue cop, green doctor, red mafia.