How does leecher level work?

[Allura]

I read some of the documents, but I don't understand how it works.

 

I see people who have 30 leech posts and 5 regular posts but they still have a positive leecher value? The the 5 regular posts are just normal posts, not shares...

 

Also is it only counted as leeching if the content is hidden? Or just in specific sections?