The window usually has a marking in the lower corner, sometimes upper. These are usually shop doors or where there is a chance of serious injury to the public. They shatter on breaking into fine shards but not as dangerous as normal shrands.
A low quality tempered glass will always scratch. Test first in an inconspicuous corner. A fine rasp/tinkle will be heard when going over. Even if its good quality, still go easy - they are much easier to scratch than normal glass.

ALLWAYS  REMEMBER  whén using  blades  or  scrapers   .. to use a   new  blade on   wet  and  soapy   glass... and  the  correct procedure is  too  hold  the  blade at the top horizontally  and then  then  move  down wards in one  smooth  sweep when at the bottom of the sweep   take  the  scraper of  and  repeat again until all the glass at the top is  finished... saying that  i allways  have a new  blade      or change it  very  often .. (with  some  scrapers  u  can flip the blade around  and  use the other fresh  edge )  one  can hear  from the  scraping sound (  wet  glass!!!)  wehther  something is wrong or  right.

As a further caution - fabricating debris is a defect found on way to much tempered and heat strengthed glass. The heat strengthened glass usually has no identifying mark like temperered does. Also on quite a bit of the bad glass you may not be able to tell if fabricating debris is present. I would never use any test or tell a customer I could "find" the defective glass.
I use a waiver that my customers sign so they know this problem is a manufacturers defect and I can't be responsible for any scratches resulting. This is important because most of these scratches are only visible under certain lighting conditions and they could have been on the glass for years and the customer might "find" them after you clean and blame you. Remeber that on a hardness scale glass is harder than metal w/ the exception of a rusty blade. Rust will scratch glass a clean metal scraper won't!
Just be careful because you never know where this menace will pop up.

Excellent info you've amassed there Karlos! I recommend that everyone read this.