I've deleted quite a few comments recently. A legitimate commenter has nothing to fear. This simply reflect a rise in comment spam with comments not pertinent to the posts in question. I am quite lenient about keeping pertinent comments even if they have arguably spam links buried in a commenter's ID. But, I will not tolerate wholly unrelated or vacuous generic comments (e.g. "great post") whose whole point is exclusively to send you to another commercial site.