Meant for non-rinseoff products like glass, surface, tile and floor cleaners.
At first I tried making some 1% solutions of several surfactants in beakers, then pouring a few mL of each one in separate watch glasses, and then allow for the water to evaporate and watch the remaining residue.
Then I realized that some micro scratches on the glass may be mistaken for cloudy residues, so the test should better be carried out in new or non-scratched watch glasses.
Then I bought some new, clear plastic shallow mini trays. Each one of them holds more than 25 ml, way more than watch glasses do. So I won't need to conduct experiments with higher surfactant concentrations.
The only downside is that they being made of plastic, they can't be placed in an oven to speed up drying, which may take a couple days to air dry.
I didn't find much info online:
From the Liquid Detergents book:
From the Handbook for Cleaning/Decontamination of Surfaces book: