Deleting EDMCS Nodes in Purgatory

I'm seeking guidance for a comprehensive method to identify and delete (what I call) "nodes in purgatory." These are nodes that have been Removed from all locations in a given dimension but have not been deleted. They're completely unused yet still exist in our record count.

I stumble upon them from time-to-time when the uncommon need arises to "add" a node that (unbeknownst to me) previously existed. I'll attempt to add the node on behalf of a user and receive a validation error that a node with that name already exists. When I search for the existing node, no results return because it's been removed from all locations. This is an easy fix; I simply switch the add action to an insert and voila! However, it does indicate a problem whose scale I have no mechanism to measure: how many of these