Just wondering if anyone has had any experence with the Sealtech process of checking for waterleaks. I have a waterleak

that I just can't find and have made an appointment with a dealer that does this process.
With all the doors and windows closed the coach is pressurized, then they check for leaks on the outside of the coach by spraying a soapy soluation (can't remember the name of the product) on the exterior components that penetrate the shell as well as the seams.
Just wondering if any one has had this done and if it really works. They said it takes about an hour and the cost is $80.00. At this point I am willing to try anything.