According to some “SharePoint is a beast.”
You may think you’re an expert at SharePoint, only to find out later you’re an expert at merely a small aspect of the beast’s capabilities.”
Source : http://blog.fpweb.net/how-to-empty-recycle-bin-sharepoint/
And I totally agree on this !
Read more here
http://msdn.microsoft.com/en-us/library/office/gg552610(v=office.14).aspx