@Mikki0 There's those of us who wouldn't even feel okay about leaving a hotel room a mess, let alone someone else's home. But there are plenty of people who think if they paid to stay somewhere, the host is their personal maid. And some people just don't see the mess- they probably live like that at home, too.
I had a lovely guest in my home share last year- a German girl in her late 20's. She was super sweet, a great communicator, smart, respectful and a lot of fun to hang out with. And she was into preparing herself big hearty meals with about 25 ingredients twice a day. She always cleaned up the shared kitchen after herself, washed every dish and utensil she'd used, but she was a really lax dishwasher- I'd find bits of food and grease stuck to almost everything she had washed (I don't have a dishwasher). I have friends like that, too- you have to rewash any cup you take out of their cupboard, because its sure to have an old dried coffee ring in it. There are people who simply aren't detail-oriented or particularly observant.
In the case of that guest, I chose not to say anything- I just rewashed whatever I found that wasn't clean. Because she was trying to be responsible, and she was just fine in every other way. She left her room and bathroom clean and tidy, she was just a crummy dishwasher.
If I had a stand-alone listing, I wouldn't be fussed if guests left a few breakfast dishes unwashed in the sink on check-out day, or didn't put all the bits of garbage in the bin, but if they left a huge pile of the previous night's dinner dishes and pots and pans covered in grease and congealing food, and the place was a general disaster, I'd definitely call them out on it in the review. But I'd try not to let it actually upset me, rather consider it part and parcel of hosting. The messy guests balance out with the ones who leave it nice.
I know you said you weren't asking for advice on how to get them to clean up, but I do think it's important to leave a check-list of expectations-what we think is common courtesy may not occur to guests. Stating that "In order to keep our prices reasonable and not have to charge a cleaning fee, we ask that you...." could help.