Our assistant moderator Antinous has noticed an increasing number of legit comments getting caught in the spam trap. Previously, it was only catching an innocent comment about once a month. Now he's fishing three or four comments a day out of it. We'll try to sort this out.
For now, Antinous says that having multiple links to the same domain seems to be the trigger, even if the links are to different pages in that domain. For example, a comment containing links to three different Wikipedia articles runs some risk of getting snagged. Avoiding that pattern isn't an absolute guarantee of safety, though; he's found a few comments in the spam trap where all the links were to different domains.
What we know for sure is that several commenters have complained that we unpublished their long, thoughtful, citation-filled comments, when in fact they'd been grabbed by the spam filter. If you have a comment go missing, let us know. In the meantime, Antinous will keep checking the trap.