My most common issue with Antispam would be the stopforumspam feature of it. While stopforumspam is a good service, if a IP ever gets reported and flagged on that service, it blackballs that IP from joining any site that makes use of that API and requires the end-user to submit a removal request of their IP.

To get a better outlook of your Antispam activity, please go to the /antispam-block-log part of your webiste.