I heard one time... 

...to test a guy's character have him walk your dog around the block.

...to test an egg to know if its raw, spin the egg on a flat surface.  
If it wobbles, it's raw.
If it spins well, it's hard boiled.  

And to add to these true tests
If its a great fabric it makes a great yoyo!

What would you expect from Yoyomama...