To add my two quids worth ...
I live in Zone 2 London and Air bnb-ed out my spare room for a year and a half. I was pretty constantly full. I'd say that out of every five people who stayed, two were a pleasure to host (grateful, considerate, tidy), two were ok (i.e. pleasant enough but treated the place like one would a hotel, not making bed, leaving rubbish for me to throw away) and one was a bit of an asshole who I wouldn't have back.
With the nice guests, it feels like a total wheeze, money for old rope. I'm a terrible people pleaser and I actively enjoyed giving them a stay that exceeded their expectations and advising them on cool things to do in London.
BUT because it's your home, if people aren't immensely appreciative and charming you can become hugely resentful (well I did!). Cultural differences play their part - for instance, the room was at the top of the house and I'd offer to carry up their bags, expecting the silly English tussle of 'no, it's fine!' 'no no, I insist, etc', 'well, thank you so much!' etc. So if they took me at my word and say, 'ok, thanks', and left me to it, I'd find myself seething away as I lugged up their suitcases.
I live alone with a toddler and never felt in danger (call me naive/foolish/overly trusting of human nature, but paedophilia never crossed my mind). Although I did get completely freaked out one day when two girls staying invited a friend of theirs into the house at night without telling me, and got very cross with them. So, from then on I made it really clear that visitors had to be cleared with me first. I didn't want to put up endless house rules on my listing, because I think it's off putting and unwelcoming, but from then on I did clearly state that.
My worst guests, for some reason, tended to be twenty something women, either in pairs or with boyfriends.
With breakfast, I didn't particularly want guests down in the kitchen in the mornings, so I put a fridge in their room with orange juice, milk etc, and a kettle, and then gave them a tray outside their door every morning with croissants and fruit.
The cleaning did become a drag, especially with one night stays.
My hosting ended when I had to sell my house unexpectedly quickly. On the day we exchanged I canceled five advance bookings, all with at least a month's notice. I was hugely apologetic, and explained that i had to leave my beloved home and find another place to live with my toddler. The reactions I got completely tallied with my general findings about the niceness of guests: two said 'absolutely no problem, good luck', two said they were a bit disappointed but never mind, and one really laid into me, saying that I had let her down and how were they going to find somewhere else for their weekend with only six week's notice (!) with absolutely no reference to the fact I was about to be homeless with a toddler.