I'm not sure if 'spam' is the correct word for irrelevant and unwanted links to other blogs/websites on a blog's 'comments' section. But although I'm unsure of the correct terminology this is what I have been receiving from time to time, and it seems to be on the increase.
One of my readers has posted to me with concerns about this, and I think they're justified. So from now on, I am changing the comments section to 'moderated', so that I can see each post before it appears and weed out any that are inappropriate. This doesn't mean that I will be censoring genuine comments, just weeding out the links to porn websites etc!
I hope everyone who reads my blog will understand and be happy with this decision.