^^ The problem is that you have people who feel they know better or can judge about something better than you everywhere - just like your aside in the comments above said - that you're now worrying about Glaswegians or Germans ^^. It was written with a humorous or ironic bent, but I don't think you would have mentioned it if you didn't feel some ambivalence about the reception.

And this is not even talking about a culture plainly not your own, like Ethiopia. So while I believe it pays to be aware of criticism, especially if many members of the culture don't like an aspect of the portrayal, but it doesn't pay to worry about pleasing everyone completely. I don't think a person can do that, whether in writing or anywhere else.

With the rising awareness of cultural appropriation the careful ally or wanna-be ally will want to make it clear that a book is not written by a member of the culture most written about in the book, though.

My personal favourite piece of crack literature is the martial arts/Australian heroine/Chinese legends book series by Kylie Chan - I totally devour it for the fun, fast-paced action and the hefty romance, but I bet if a true Hong Kong Chinese read the book they'd be doing more than roll their eyes at the Mary Sueness of the heroine who saves everyone's bacon, so that all the good guys (and even the king of the demons) love her, while she solves all their problems.