Makes me think of how many random objects end up down air vents, especially in SFH rental properties with families ( children) ... Fixing the furnace/AC accidentally turns into toy recovery and trash disposal.

Even better is when you do a bathroom remodel on a mid-century bath, that had the razor disposal slot in the medicine cabinet, all of the used razor blades would end up down in the wall cavity.

Are you sure there is not a USED COMB SLOT on the vanity?