I (also on Dreamhost) have been having identical problems to missmarymac and basically put it down to a failed update that would later sort itsself, but ultimately it was that link to halfelf’s page that fixed this for me.
Link:
http://halfelf.org/2014/not-the-bug-i-expected/
Notice the various attributes for “comment_id”?
http://i.imgur.com/DKx5K9V.jpg
Well, mine looked like this:
http://i.imgur.com/7jqZpNg.jpg
So, I prettymuch copied it from the picture, to this:
http://i.imgur.com/RUG5WG5.jpg
And instantly, the spam started flooding in 😀
Never have I been so happy to see it.
I still can’t delete comments properly, and posts sometimes (probably due to caching?) will list “3 comments” after I’ve deleted them from the database, but hey, actual comments.
I didn’t manage to salvage the old discussions, which is a shame, but thanks everyone.