Do they have to remain in their original location with the "moved" mark? To me they seem to clutter up an extra forum rather unnecessarily. Can they not just be straight shifted to the new location, or is it a quirk of VBulletin?

The person who started the thread might be looking everywhere for it. Some might even feel offended.

Ya, BL more or less said it. Spam just gets moved w/o the marker but legit stuff gets the marker so readers know where it went.

Ideally VB would let you set auto-expiry dates on the markers but that's not available in our version.