I filled the meta description field in the "SEO / Meta data" part of the category page with the following:-
Hard Drives in 3.5" and 2.5" sizes
I then noticed that the literal HTML generated for the meta description in the header was as follows:-

Note the content attribute- this should end with the double-quote following 'sizes', but due to the first double-quote in the description (apparently) not having been filtered out, it is closed following '3.5' and hence the remainder of the tag is messed up.
I'm guessing this wasn't intentional? At the least I would have assumed that double-quotes would be filtered out or converted to single quotes.
- Smich