When ppl buy, I look at the feedback they leave for others, as well.
I had one lady, I don't think too many sellers, ever pleased her. I thought, "Oh great, this will probably blow". I did the package up real good and she left no FB. That was fine with me! She got no FB either, no biggie.
Etsy, you can't/don't leave FB for the buyer, that's fine with me, too.
If you leave positive feedback, then your buyer turns in to a daymare........ nah..... I ain't changing what I do either.
If your buyer turns into a daymare, what effect does your having left positive feedback have on the situation? I don't see that it would effect the situation at all, unless I am missing something. The best you could do is leave a positive feedback with a nasty comment, but would good would that do?