I read my T's psychology today page once and cringed the entire way through and haven't reread it since. There was a misused semicolon (gasp!) and a lot of really awkward and cheesy wording. It wouldn't have really bothered me if it was someone else, but it bothered me that it was sloppy. He's much more eloquent when he speaks. It kind of felt like seeing him in public wearing cargo shorts and socks with sandals instead of his normal business causal attire, if that makes sense.
Semicolon abuse bothers me more than most grammatical mistakes because you don't really need to use semicolons, so if you don't know how to use them properly just don't use them. Misuse of "whom" when it should be "who" also bothers me a lot more than "who" when it should be "whom" for similar reasons, because it feels like the person was being pretentious and failing at it. But that's just me being pretentious.