There are three ways.

a/ If an object was deleted and it still can be found on the Trash can main tab (or, if an edition was deleted, but still can be found on the Editions main tab under Undelete option), it means it’s not purged.

b/ By doing SQL searches in gn_SpikedTable that contains ids of all deleted objects.

c/ By looking at the log of tasks, more precisely to the CleanupProcess: