OTC ratings are useless unless the trading person is signed in and gpg identified with the bot. It's also useless unless you can look up other users who gave ratings and judge if they are fake. If all else fails you can ask the room which is why it's the best system so far.
For a web app you could do the same thing with Yubikeys or other 2FA, but you can't ask a room of people if DerpMaster(+10) has valid ratings or not, and we have to trust the security of your site and you personally from not inflating ratings or altering them. In addition if you're American, idiots can sue you for slander if somebody leaves a bad rating they do this on ebay all the time to reverse a negative rating, so now you can't leave negative feedback only positive or neutral.
The only rep I've seen used is OTC, btcjam, your account here, ebay, and amazon. You should just become an escrow agent with OTC rating the more the better as I'm always looking for one at various hours. Then your site people can optionally trust you or the people's rating who they are trading with.
Yes, of course people would have to identify with the bot. Everything would have to be safe in this regard.
The site would never run its own rating system as I don't believe in doing so. I think the rating should be as standardized as possible. Right now, it seems to be Bitcoin OTC.
As far as building trust for me as a person, and in extension to the site, I could definitely act as an escrow agent.