When I wrote foolproof, I had 2 things in mind: Aa guest for a few nights will probably not use a thing he does not understand. A longterm guest will use it and force it to serve as he/she thinks how it should work.
In that sense, I have rules for not reprogramming anything with buttons on it and place the router at unreachable hights, removing the ladder. I still dream of getting a transparent case for the front of the hifi set with 3 holes: on/off, loudness and source.
The more dangerous habit is neglect. In my experience, in a small space 3 weeks of vapour ous showers, not opening a window, creates an ambiance to throw you back out, when you open the door at home coming. 6 weeks create damage, especially if people let flakes of water stand on wood. I varnished the surfaces in danger, although I'd prefer them oiled, but even that is not always enough.
That's a far from exhaustive list 😉