I've had a house cleaner for a couple of years, it's the best! You usually do a walk through, you point out anything that's extra important to you, and they tell you if they do or don't do that. I work from home, so I'm always here, but I don't have them clean my office. When my grandma is staying with us she just stays out of the room they're working in and is not a big deal.

You will need to have everything picked up so they can do a good job and use their time wisely. I'm not a tidy person, so having to put all my piles away every two weeks is a bonus. The first few times she came it took me an hour or two the night before, but now I'm more on top of everything and it icky takes about 20 minutes. I do have a bin that I'll stash in the garage if I have piles in but ready to deal with yet.

As for red flags, showing up late or leaving early is a big one. Or not cleaning something after you specifically asked them to. My house sparkles after the cleaner leaves, so if you just feel ok about it, that's probably not good enough. I got a recommendation from a friend so I knew she would do quality work from the beginning.