I would have thought that there would be a built in symptom for this but there isn't (only for real snapshots which would usually work for this issue but I know of times when consolidation is needed but there are actually no snapshots.)
What about using the Virtual Machine Metric: "Waste % > 0" I do not know if this will work but worth a try?
Because it's not a vSphere alarm (Instead a "Summary: Configuration issue") I can kind of see why this didn't make it into vROps - but it should be!
I would be interested to see if there is actually a snapshot file associated with this VM, I suspect there is nothing in snapshot manager, but do you see any on the VM folder on the datastore?