I think such thing are unavoidable, and i would not suggest for a stricter registration as of now lor as i believe it may put off some people from joining in. Thus removing and banned them as they comes.
However i would suggest to have a "Inform Mods" button. This button will let the members to trigger the mods when they see any unsuitable threads or threads that needs the mods assistance. For this will speed up the reaction time to get the thread removed or assistance. The mods will also have a easlier task of maintaining the forum.