Detective sim?

I've played a lot of it and I don't think that genius trait helps much. My best detective has been Don Lothario, even if I thought he'd be the worst. He never failed on analyzing evidences, for some reason. My genius Sims, even level 10 on logic, have never been better. Don also had the noncommittal trait that made him tense at work, but it didn't seem to effect on the performance.
I've had Sims with different traits as detectives and I haven't noticed much difference. The one thing that seems to help is to get an observant reward trait. It helps finding out the right Sim to arrest. I usually get that for all my detectives as soon as possible.