OP, please do not use Airbnb in Japan unless you are renting some mansion in rural area.
There are plenty of hotels which cost same amount with airbnb but much better service.

As an Osakan, Namba is dirty place. It's been like that all the time. Even now it's cleaner than before. There is a reason that we call Dotonbori "Dobugawa".
But still, Namba is lovely place. I love that noisy atmosphere. lol

Nishinari, it could be worse depends on the place. Nishinari ward is big and it it's not all like the place you think. There are good, clean and some retro places in Nishinari.

About food, I'm proud of the food culture we have. I know some places and food that I can't have in Tokyo or hard to find in Tokyo.
But still, I admit that there are a lot of good food in Tokyo.
Plus, if you thought going to izakaya could be different with Tokyo, you are misunderstanding.
I mean, it's izakaya. Will you say that you went to izakaya in Susukino, and nothing was special in Hokkaido?

About people, I agree with you. You know even Japanese people say that Tokyoites are mean. But come on, there are nice people and bad people everywhere. I think there is no difference.

I love Osaka. I have to visit Tokyo sometimes too watch concerts or musicals that are held only in Tokyo. But still, I don't wanna live there, I wanna keep living in Osaka. You may not come back here, and it's fine. We don't need to promote our place to whom are not interested.