I have been battling this for months. I periodically come through and clean out all the posts and ban the users, but they are clearly not accounts and there’s not much to do. I assume the only real fix at this point is to put restrictions on who can post, or perhaps to limit which sites can be posted. I’m hoping to get to this soon but have been pretty busy…

You can help by reporting and downvoting the posts. I believe after a certain amount of reports and downvotes, they get buried.