Not saying this is the issue people are having, as I have no idea what issues different people are running into, but...
One thing to keep in mind if you've got a household with multiple sims is, be wary of half walls and glass doors (possibly - haven't tested glass doors specifically).
The only "walls" I know of that count as actual walls, in terms of maintaining privacy and avoiding the embarrassment interruption, are full walls and the highest tier of half walls. You can safely assume that pretty much everything else won't keep prying eyes out, even if it physically seems like it should.
I mention it because it's one of those things that can catch you off guard, especially if you're using lots from the gallery. I had one lot I was using for a time that blocked off the toilet in a cute, creative little way by using hedges. Only problem was, even though the hedges physically obstructed the view and realistically shouldn't have allowed the embarrassed interruption, they didn't count as actual walls and there was a cooking area right on the other side, so any time someone would go to cook, they'd get interrupted by the sims trying to tinkle and vice-versa. Very annoying and very easy to miss.