I've been thinking a lot lately about the need for better form security, and good ways to accomplish that.
We currently use captcha codes to screen for bots, but that's annoying to users and may not work forever.
I think that we need a more intuitive, organic system for screening bad comments/contact form submissions.
One option that has come to mind would be trying to screen comments for things that are obviously not words, in addition to screening for duplicate comments. E.g., when a spammer on Facebook, Twitter, or a comments section is stopped from just posting the same thing a lot of times, they add garbled letters and or numbers somewhere in the post to make it "unique".
If it was possible to screen out obvious not-text, this could be overcome. If you could go a step further, and screen out posts that obviously have words placed in for no reason except to make the post "unique", you could force the spammer/scam artist down to only use repetitive post options which actually make gramatical sense.
At the very least, you could have posts be flagged for moderator attention if they looked similar but which just had random garbage added in for no reason. This would significantly reduce a spammer's ability to keep spamming, even across multiple accounts.
Could it be possible to screen form field results for random word and number combinations, and words thrown in just to make a post "unique"?