Some of you may know that a form can be done via a simple cURL script on a remote server, this has happened to me, and it was a pain in the butt to deal with. Anyone know how to prevent it, besides a CAPTCHA?
Add a hidden variable to the form and check for it's presence and correct value before processing the posted data. That should weed out at least some of the spam. You could also try and check the location the form was submitted from and make sure it's from your domain and not someone else's.
True but the point is to stop as much spam as possible while still being reasonable in the methods used to stop it. You can't stop them all but the more you stop the better.