Supplier Purge - How can you tell why a supplier is not purged?

I've seen the supplier purge criteria section of the Payables User Guide, and still am curious why some of our suppliers are not getting purged when I run the payables purge process for suppliers.  Is there any way you can see what causes some suppliers to be purged and others not to be?

Also, does the process really even look at the last update date of the supplier?  We have some suppliers that it appears to me like they were last updated after the last activity date and are still set to be purged.  Any insight anyone has into this would be helpful.  Thanks.