Our construction clean bids includes removing paint, stickers, caulk, silicon, and other construction debris.  We normally do this with a very sharp razor blade.  Our soaps provide extra lubrication to protect the glass.  Then we clean the window again, to leave it Clearly Clean.  We take extra care with tempered glass, often times using 0000 grade steel wool, which takes more time but protects the glass.
 
 If  you are concerned about scratched glass and how it happens please see this document.  We do the utmost to protect your glass and clean it in a effective way.  However we are not responsible for scratches that have been caused by other contractors or fabricating debris on tempered glass.
 
Also we have detector to detect tempered glass and Low-E coatings.  If you need to check correct installation of tempered glass, or Low-E coating we can provide this service.  We have often in the field noticed Low-E coatings on the wrong surface, sometime even exposed on surface 4.  (Outside of the inside pane)