How to identify a Meth Lab

"Keep in Mind when your face with this decision ...  retired police officer wrote the following:

As a law enforcement officer, I have been approached
 
by several people lately wanting to know how to identify a Meth Lab
 
Following are four photos.
 
I think it's  pretty obvious which one is the Meth Lab.
 

I hope this helps.  Let me  know if I can be of any further service in this  matter.