While mistaking e.g. "there" / "their" / "they're" annoys me, I acknowledge that I'm stubborn about that stuff. Messing up details in a big formula or algorithm that people are going to use as a reference is just sloppy, though. I really appreciate authors who write in a (possibly personal and ad hoc) literate programming system that automatically extracts and tests all code samples.

I don't understand your "makes me engage with it a little bit more" reaction, though. I really don't. Could you explain?