I thought tags were auto-removed when no longer used, but I've got some tags that have usage '0'. Are they cleaned up by a cron job or should they be automatically removed as soon as they're no longer used? Would an addon like MediaGallery or Vaultwiki potentially interfere with this? Both integrate with the XF tags system. Will tags with usage '0' still get listed in the Sitemap? Mostly they're tags that were used by spammers, so some of the terms are quite spammy--definitely not something I want to be telling Google to come checkout.