Ok, a few things to address, but I agree with most if not all you've said.
My only Air B&B experience in Italy was in July 2023, in Bari (southeastern on the boot; top of the heel). The only caveat of the whole thing was an elevator issue, which was rectified (it was on the top floor, and one day it wasn't working so we had to walk down all the stairs, and it was 115F outside, and you know the interior of the building doesn't have a/c). Since I broke my leg falling down a flight of stairs during lockdown, I still get anxiety on them today.
Everything else about the experience was perfect.
My only experiences not in the south are limited to 25 years ago... I've spent a few trips on the bottom of the heel at my in-laws homes, and the south in general, is opposite of the south of the US in terms of being progressive. When it comes to more liberal topics such as homosexuality, the south is surprisingly friendly. Even the town priest walked up to me and was very welcoming. The places you may come across more right-leaning ideologies are in central Italy and the north. Of course it's not everyone, but in general, you'll see more bigoted people in central/northern Italy.
It's tricky for me to give an accurate, unbiased reaction to the country though because when I go there, I am fluent enough to be confused as a native, and they always peg my accent as southern (which has to be from my late fiance's and my grandmother's/father's influence). You will still get the reaction from northerners that are against the south... just like southerners who are against the north, but I'll save that history lesson for class.
Small towns in the south are incredible.. I stayed in this tiny hotel... 40€ a night, air-conditioned, breakfast included (granted in Italy that's just a cornetto and a cappuccino, but that's all I eat anyway), WiFi, so clean you could eat off the bidè, and the hotel owner's wife treated me like her child. I came home one night and she washed and folded my dirty laundry (seriously). I approached her about it, which, I understand most might find this a huge invasion of their privacy, but when a man is traveling alone (and she knew I was a widower), the "mother" in them comes out. In fact, she didn't think I was taking good-enough care of myself, so she'd tell me to go into the kitchen and help myself to peach juice, taralli (for those who don't know, they're the Italian versions of pretzels but have a texture of like a cracker), cookies, etc.
Southern Italy has become more like home to me (aside from my fiance being buried there, it reminds me of my own family). My only hatred is for the blistering sun and summer heat.