I HATE gender-neutral pronouns. In refuse to use "zie" and "zir" -- I use "them" and "they" if for no other reason than I can keep them straight. And if it was good enough for Jane Austen, it's good enough for me.
My impression is that they are used ungrammatically about as often as any other pronouns. Some people are good at grammar, and others aren't. If I can understand the meaning, I'm not going to bust someone for using her instead of she, or zir instead of zie (unless I'm very good friends with that person, in which case I might do it as a tease).
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