I'm confused about the Social Worker, though. I've taken no chances--I have one as a character in my Legacy 'hood, but she is really a normal Sim created in CAS with the unlocked SoWo outfit. But I've certainly heard of people marrying her in with no ill effects, and that she is a sim with ordinary wants, etc. What is the problem with the Social Worker?
The ony thing I found with the social worker made playable is she still tries to walks through walls on every lot. Except for this she acted like any normal sim.
Some other charaters have strange behaviour, like The nanny, the burglar, the grand vampire, the streaker, the diva/Mr Big, the uni mascots or cheerleaders, and perhaps others I don't remember now.
Some behave like normal sims once playable, like the maid or gardener, the mailperson, the paperboy, the pizza delivery, OFB reporter...
It seems Pescado said all, it is probably better to avoid marrying a service NPC at all. Even a named character of the basegame like the burglar or the nanny retain their strange behaviour. What real damage it can cause to the game is beyond my knowledge.