Moderating Blog Comments

I remember a discussion some time ago on Writers Talkback about blog comment moderation, and the dreaded 'Captcha'. For the most part, it seems that people are less likely to comment on a blog if there is a moderation process in place, and I can understand that, especially as Captcha seem to have done their best to make the darn things practically unreadable whether you're human or not!

On the basis of this, I elected to leave the moderation process off my blogs. I get a notification that a comment has been made, and I can then go and choose as to whether this is suitable to publish, and publish, delete, or mark as spam as appropriate.

So far this has been working just fine. Until a few weeks ago, that is. I did a post called 'Catching Up' and for some reason, this has been nabbed by some sort of weightlifting/gym sort of organisation, and they seem to think it's ok to keep posting on there with completely irrelevant, ridiculously worded phrases. From the looks of it, it seems to be directed from Russia. And frankly, it's bloody annoying!

As I'm now getting them on that post several times a week, I'm seriously considering putting the dreaded Captcha back on, as much as I'd prefer not to. So, my question is, does having this process seriously put you off commenting on a blog?

I'd be grateful for any opinions on the above, or if you have any other ideas on how to avoid the spammers, I'd be grateful to hear from you.