Sorry for my ignorance, but was is a " scratched glass disclaimer " ?
For builders cleans.
Some glass is damaged by the builders & installers, even transporting it from the factory can leave marks if its not properly protected. This damage is often hidden under the dirt & is only seen once cleaned,... so the cleaner gets the blame & there have even been ppl who sued the cleaner. The waiver explains how glass gets damaged, why its only seen once its clean & absolves the cleaner of any legal worries should the glass be damaged.