There are only two options for any blog. Allow no comments at all; or have a spam-filter. No way can you moderate by hand all the comments that arrive. For example, in the last six months — reports the plug-in at LogicMatters — there have been 72,664 spam postings in the comments here filtered out by Askismet so that I never even see them, never have to deal with them.
Askismet does a quite brilliant job, then. I’m certainly not going to turn it off! But apparently it can err on the side of sternness. If you try to make a sensible comment here which never gets approved, then it may not be me being unfriendly! If your words of wisdom seem unappreciated, you can always try re-sending them as an email.