Happened in my game today.

There seem to be some minimum number of tasks to take care of that a mid-range performing maid (maybe not the total goof-offs) must take care of. If they just don't have time to get to them all on-screen before their shift is up, the remaining things will clean themselves up automatically as the maid leaves the lot. Dirty dishes fall into that category, from what I've observed so do obviously dirty (not just kind of dirty where you can't see it yet) sinks, bathtubs, showers, kitchen counters, and toilets -- it's really startling to hear all of the toilets in the house flush at the same time when this happens until you get used to it. Not sure, but also maybe piles of garbage on the floor or ground and maybe old newspapers to be discarded, puddles needing to be mopped up.

Beds being made, laundry tended to (which my maids almost never do very completely), leaves being raked, I think maybe stuff like books and toys being put away need to happen on time and through animations or they aren't going to get done at all.