Do you need some inspiration? In that case, how about some black market stuff? Sell services like lending out your bot and it comes back a bit damaged or something in a sexy way. Scratches and stuff like you said. Perhaps some grafitti that you can clean by buying something cheap. People love maintaining stuff, that's why tamagotchi blew up. And personality traits might be gained, which might be more difficult to implement but that'd be hella cool.