Is anyone aware of a product you spray on the paint which then colors the surface contaminants so you know where to clay and when you're gotten every last spot?

Sort of like the iron-x spray colors the iron particles, or (you older guys might remember...) like those little red tablets you used to chew as a kid which colored the plaque on your teeth so you knew when you had brushed all the plaque away.

If there's not one, someone should develop one! Getting those last few tiny spots of contaminants can get aggravating with the baggie test.

Granted there are many different possible contaminants but they may all be different enough from the chemistry of cured clearcoats, and may mostly share some common chemistry, that such a product at least seems plausible. It may not indicate every contaminant but as long as it picked up the most common ones that would be great.