SEO Spam messages via form on my website, what's their actual objective?

I get a load of spam messages arising through the contact/comments forms on my website; exactly the same wording every time (different name - today it claimed to be James Cameron):

I’ve emailed these people back before (from a disposable account), pretending to be interested, just so I could subsequently tell them to get lost, but they never respond.

So is it just a scheme to try to get a contact email address off me, to be sold on to spammers? If not, what could possibly be their motivation?

They only want to put the links to their websites on your, and a million other, websites. They aren’t soliciting custom nor wanting anything else from you.

Sure - that would make sense for the comments stuff that gets published on the pages (and I do filter out some examples from that), but in the main, the messages as quoted above are just coming in via the ‘contact us’ form.

I guess maybe they don’t get the distinction, or maybe it’s a bot that has just detected a form and is blindly filling it in?

That sounds likely.

Of course it can be very difficult for a blogger to erase particularly flattering comments of an Oriental floweriness complimenting one’s posting style with lavish exuberance.