there's a lot of auto-bots out there that crawl boards and post things, sometimes faster than an admin can pull them down. You will not find any board out there that doesn't have this to some degree or another - unless they've got admin on board 24/7 in every time zone.

Admin here does a great job. I've got NO cause to complain. I know of a few boards where the bot-spam is rampant because the moderators only check it once a month or so.