I don't care about poor spelling or grammar as long as the comment is understandable, with a few exceptions. Bad spelling and grammar in articles and reviews can annoy me mildly as these are things that people should prioritise more in serious writing, but the main thing that pisses me off is when people misspell or don't use propar grammar when they're complaining about other people's grammar[footnote]I once saw someone on Youtube who whenever they spelled the word 'skills' spelled it with a 'z' criticise someone for spelling. It was so hard to restrain myself from responding both towards their use of ad hominem and towards their hypocrisy.[/footnote]. But that comes more from a hatred towards hypocrites than a grammmar Nazi personality. Also, I can't stand all-caps.
If I use bad punctuation (a.k.a. below my personal standard of writing; I still struggle with some pieces of grammar myself) or misspell something in my own work then I will edit it out pretty quickly. But other people's writing I won't mind as much as long as it's not something as serious as an article or review or short story etc. and even then I'll try and not be offensive with my criticism.