I've played themed hoods since about the first week of TS2 release in 2004.
I don't have many rules. If I get a whim to do something that's what I'm going to do. No rules, my way or the highway. :p
However, if I play characters, then they can't behave outside their intended personality.
What I mean by that is a Sim who is shy, homemaker, family, mother, loves baking would never show up at a dive bar like the Blue Whale.
This works for TS2 and TS3.
What most people don't know about TS2 is if you take a Sim to the same community lot a few times then the next time you go there with another Sim your previous Sim will also show up, everywhere you go, if you took that Sim to those places. So, finding Sims in the game isn't all that hard. You know where they will be. To keep the game from spawning Mrs. Goody Two Shoes at such places where she would never be caught dead, you would never send to her to them. It's not to say the game won't eventually send her there as one of the patrons of the place, but it lowers the odds if you don't.
Barnabas would never work as a DJ, nor sell coffee, nor work behind the bar, no matter how poor or starving. My Sims have to fall within the guidelines I set for them. If he is a serious Sim then no, he will never juggle bottles, and even if an interaction is available but I think doesn't fit the Sims then it will never be clicked by me.
Consider he is a vampire, well the rule is, he is never going to want to get down and line dance. Nor is he going to ever want to play on a refrig. or the bathtub. Most of this controlled by traits (personality points) but if any interaction or action is there then I won't use it because it wouldn't fit his character in my head.
Those are the type of rules I set. Would Willie be at the Blue Whale, yes, would Elizabeth be at the Blue Whale, No. But unfortunately the more you play a Sim in TS2 then that SIm is probably going to show up somewhere whether it fits their personality or not. Evenutally. Moving them to the bin for awhile while I play other Sims sometimes cuts all that out and then in my story they have gone missing. lol
Aging rules: I have a mod that extends their lives, (38 days) so middle age is about 27 days before aging to elderly. I play with aging on until I get the Sim to that age, and someone else in the household may be much younger but an adult but 35 days away from aging which makes them seem younger to me. I do this sort of thing for all households in a themed hood. Then aging is turned off to keep them at these stages of life.
Those I feel are older than a 35 days or 27 days are aged to 20 days etc. It's all in my head, but I keep doing it. lol
I don't have any rules but if I play a themed hood then yes, characters aren't allowed to do things they wouldn't do. No soup for you! lol Stop making a fool of yourself, you silly Sim showing the world you can't dance. Evil Sims have to be evil, good Sims must behave with manners, mean, grumpy kids must annoy, aggravate, torment and destory. Lazy Sim should never clean dishes..sloppy Sims better not start cleaning the dishes, or they will get zapped. One thing I really hated is when devs of TS2 changed the code to make even sloppy Sims clean up dirty plates because someone back in 2007 complained.