People on double my salary who do not posses basic reading literacy and who cannot even be bothered to spell my name correctly.
This is a cheeky thing to say, but if people consistently write with regular spelling and grammatical errors, I instantly assign less value to whatever point they're trying to make.
If they can't be arsed to state their position coherently, why should I pay them any mind?
Also, when predictive text not only messes up my spelling, but replaces entire words with completely different words, completely obfuscating my meaning.