It's not uncommon to see HL's without a ventilator ball in some store displays. Especially, if the general public can reach into a display and handle a piece.
This also applies to HL's with free-standing trees. It doesn't take too much mishandling to break something off.
It's a real shame to see a damaged HL, especially the ones you mention in your above post. I would find it hard to believe that a person would actually cut a ventilator ball off a piece. My guess it's a cover up for mishandling. This person probably bought these items for a small price and is trying to make a profit on it.
Bob