Quoted from NorCalRealtor:
Waste of money. People mistake my clean glass for invisiglass.
I can see a huge difference...immediately, between HD/Invisiglass/PDI vs regular glass. There is no comparison.
Having said that, I know that there is no shortage of people who share your opinion. I will never understand it myself, because I see such a huge difference, but apparently many people don't notice the difference to the same extent.
Believe me, I wish I *didn't* see such a big difference, it would save me quite a bit of money if I didn't.