Total number of documents in a database is less than the number of PDFs?

How is this possible:

As you can see, there appear to be 1005 documents in this database, but in the smart group “All PDF Documents” there are 1163 items. How can the number of PDF documents in the database be more than the total number of items?

All documents is not a default smart group, which conditions and scope does it use?

Not sure what you mean. I created that group (it’s not a smart group) under the database “work”, and then dragged all my work documents into it. But you can see the same number next to the database itself, above “all documents”.

If I am interpreting your picture correctly, you have 1005 unread records. They are all contained in your group called All Documents. Only groups provide a total count; when there are unread documents, the group name and count will be bold, and the count will show unread records. A count next to the database name is always a count of unread records AFAIK; when there are none, no count is displayed.