I saw these first hand at Daz's last night.
The stickers are effectively a super thin brittle plastic (similar to say an insert decal) If you so much as touch them then little bits break off. Krylon'ing the front of your glass would look terrible, but it does seem like if it was not sealed with something then it is all just going to drop off over tim
Sounds like someone ought to speak to CPR and get them to do a run of repro backglasses...