Agreed; it IS very low here, compared to most other sites, which is why I think the ones that get through stand out so well. And that's why I think having a human look at things would be better, and would probably deter spammers. Bots aren't getting through for the most part, but what DOES happen is that you have someone at the spam-factory register, and post the aforementioned junk to get their first few posts in. After that? Spam, or editing the junk to include the links....and they also shove their junk into their profiles too, and I'm not sure if that gets web-scraped/indexed or not.

Regardless, banning the user while retaining account seems pointless, since any spam posts they make remain. I'd nuke the account, so ALL traces vanish. And reporting things where mods haven't been on in years often takes a good while...in some cases, I've seen one particular mod flat ignore reports.

It's not only their posts, also their profile pages that contain spam links and what I assume are keywords.
And as TB0ne pointed out, a fairly new trick is to come back later and edit spam links into inoccuous posts.