Earlier quoted context omitted.
They mean something, i.e. that they "are in their index in some form." I've been blacklisted before, and when you're blacklisted, you don't show up in site: queries. That said, I wanted to acknowledge that this isn't ranking data. However, perhaps as a result of this post, I'll be able to get some and re-post those results.
I'm sure you would agree with this but in case others are reading, simply blacklisting these sites wouldn't be the best thing to do. Many are simply expired or parked pages.
Google visits domains all the time so they should be aware quite quickly when things move from spam/parked to non-spam/non-parked. Therefore, I don't see why they shouldn't all be out of the index until they have useful content on them.