During the stay, I believe it is guest's responsibility to clean after themselves, no matter if they stay in a private room with shared kitchen/bathroom or in the whole apartment/place by themselves. Just keep the place tidy, it is not that hard...
Do not trash it and leave it thinking "the host will clean up after me anyway"... Yes, we will, but we do expect a level of adulthood if you are renting out a place...
I do not expect guests to vacuum, mop, scrub the bathroom, put linen in washer, do a thorough cleaning - but I do expect the place is left almost as they got it, at least about the kitchen (clean dishes and leave them drying or load and start the dishwasher) and maybe bathroom (get the fallen hair out of the sink or shower and put them in the bin, don't leave trash around on counters but put them in the bin, and please please, scrub and flush the toilet after yourselves!).
When I rent out a place, I always think about hosts and how much they'll have to clean after me, so I rather take one hour before leaving the place to wash the dishes, clean the countertops, put used towels on a pile and sometimes even strip the beds.
After the stay, hosts go through a great deal to make the place clean, tidy, disinfected and ready for next guests - we basically do deep cleaning everytime a guest leaves the apartment. We need to vacuum the whole place (even sofas and bed mattrasses), mop the floor, wipe the dust and clean all kitchen countertops and sink + appliances like toaster, oven, microwave and cooktop (you can't believe how dirty they can get if you miss just one cleaning), change linen and towels, wash them, iron them, check for stains, sometimes replace the linen and towels too if they get torn or stains don't come out... And if someone leaves a big mess behind, we need to clean that too.
Cleaning supplies and clothes detergent cost a lot, especially if you do a turnover every 2-3 days as it is usual at our apartment. Guests also use the detrgent we provide to wash their clothes and dishsoap for kitchenware. We provide all of it in our apartment to make the guest as relaxed as possible and have everything at their fingertips.
That is also why some hosts charge the cleaning fee. In the cleaning fee, there is not only cleaning after guests, but also all the little details that make your stay easier.
We basically do all the cleaning in-house, but we pay a worker for 2-3 hours of cleaning, changing linen and putting them to wash in our washing machine and dryer and sometimes also ironing. The extra we need to pay is extra water that is used for cleaning, electricity, detergent for clothes, dishsoap, dishwasher tablets/powder that are provided in the apartment and that we use for cleaning, and also breakfast items that we always leave in the fridge and cupboard for our guests to take. All in all, the cleaning fee mostly only covers the worker and some supplies (cleaning workers charge roughly 10-15 € per hour here in Ljubljana), everything else is included in the nightly price.