The reason these work better than baby shampoo or other diluted detergents, is when water gets in your mask, it tends to wash away the detergent and you get a foggy spot. From the description, this stuff stays on like sea drops. Dish soap and baby shampoo worked fine for me 99% of the time, I switched to sea drops for that other 1% when I don't hold my junk tight enough when stepping off the boat and get water into my mask.
Feh. I use BS to demo mask removal and replace in all kinds of conditions (cold, warm, salt and fresh) and never have had a problem with BS “washing off”. I suppose it depends on how it’s applied. I use a spray bottle with 30-70 BS to H2O and spray it in immediately before splashing in. Never failed me yet.