[ryanwanger]

Blocking any spam that contains a link is helpful, for sure, but doesn't get everything. Every few months I see waves of comments like: "Really graet article. We need more people like you in the world."

Each comment has exactly one pair of transposed letters. There is no product being pitched, and no url (we don't display or link to email address either). It's baffling.

[eli]

Some blog platforms whitelist comments from people who have had previous comments approved. I'm pretty sure these meaningless (but positive) comments are an attempt to get on that list.

[zalew]

yes. also some platforms (mostly forums, less of blogs) allow editing of posts, so forum spammers sometimes post meaningless crap only to replace it later with spam.

[stcredzero]

We should be able to detect that by looking for large numbers of posts with small edit distances. That will contain false positives, but looking for very large numbers should mitigate that.

[sedachv]

> Each comment has exactly one pair of transposed letters. There is no product being pitched, and no url (we don't display or link to email address either). It's baffling.

Sounds like they're doing what's known as "Bayesian poisoning" (http://en.wikipedia.org/wiki/Bayesian_poisoning) ahead of time to open the door for later link spamming.

[dkokelley]

I would guess that the transposed letters are used to keep tabs on where their comments are live. It could look innocent, as if it were a human typo, but later the spammers could run a search and see which sites are trusting their comments in order to either edit them later or use their trusted account to post spam links.

[coderdude]

Those comments could be used to make automated spam filters less effective. Spammers could post comments that would normally be labeled as spam, but do not contain any URLs. Over time a spam filter would have a harder time distinguishing between cut-and-dry spam and real comments (assuming the admin is marking those spam comments as ham).

Also, I'm a fan of not allowing brand new accounts to post URLs in their comments. It's a no-brainer.