It really just depends on the maturity level of the person who receives the pm, sometimes. Some people can't take criticism at all. Personally, if I received a pm that something I was posting was illegible to others for whatever reason, and there was something that I could do to fix it, I sure would take that feedback in the spirit in which it was intended and I'd make every effort. If people get upset by receiving a kindly-intended pm, well, that's on them. Things can only bother (general) you if you let them.
The goal of communicating is to be understood; if no one understands you, or bothers to try because it's more difficult than usual, then what's the point? If someone wanted to post something that no one else was going to bother to read, then just have a blog.