Search Workflow is empty / workflow state is empty. No coherent resutls

You can't search for something that is not there. When there is and never has been a workflow on an object then the workflow and state properties are not present on that object.

You could use a View that shows your societes, add Workflow as a column and then sort by that column. Objects without the property will then be at the top or bottom of your list depending on sort order.

Hoo; What does is empty means exactly then ? A value which has been filled and i now empty?

Exactly that.  It means that the object has a specific property, but that the property value is empty.  Unfortunately there is no current way to search for objects which lack a specific property.

Exactly that.  It means that the object has a specific property, but that the property value is empty.  Unfortunately there is no current way to search for objects which lack a specific property.