nice info about that traits on wiki...but it dont give much more info about thier real effects. e,q on that pretty voice - it just list that effect on them need to be confrimed, but yet, it say nothing about which occupations/works they are.
and will REALY love when starting new game, player should give more traits to his slave, than just only one, say max 3 - 2 positive+1 negative, or more negative ones, and to get 2 positive you rely have to select hegative too.
You must dig into the code, as suggested by d.stu: open the traits.gd file, find the effects and look for them inside the ".gd" files.
For instance the effect of "Pretty voice" is "pretty_voice": since no .gd script mentions it, the trait is still not implemented (most likely).
If you open "jobs&specs.gd" instead, under "storewimborn(person)" you will read:
if person.race.find("Tanuki")>=0:
bonus = bonus + 0.3
supplyprice += 1
which means that a Tanuki, when working at the Winborn market, earns more gold (+30%) and sells supplies at a higher price (?).