indeed, we can often clear up all the posts by clicking view all posts.
then just check all their posts and move them to a single off board place.
however generally (because people often reply to threads saying "Reported!") we have to click view all posts, then open all the posts in a separate tab check all the posts, and the posts that quote the spam and then move all the posts to a single place.
mostly reporting multiple posts by the same spanner (not a typo) won't help getting them all cleared up assuming that we do remember to check all posts. but it's generally a nice enough thing to do as it does make sure that all the spam is cleared up just in case we don't remember.