Well, first of all it doesn't strip any tags, which can cause issues if you've got a snippet or chunk in the first 200 characters. It likes to include the snippet results above the header, not necessarily in the head itself but just after it closes, and said snippet errors into an array, chunks just appear.
In the content, or template, tv, etc... snippets fail again, chunks appear.
You can override it by including "something" in the introtext field, but that doesn't fix snippets. They still array.
So yeah, strip tags is a problem. (but you're not stripping) I'm just using
<meta name="description" content="[[*introtext]]" />
and making sure something is entered for the time being, till somebody figures out a good solution.
Bob had an idea, one of his handwritten snippets IIRC. I haven't tried it. Will have to do some deep searching to find it.