No disrespect but,
It's snake oil, falsehoods, unless that stuff can dissapate storm cells located up in the sky, it doesn't work, the ones who think it worked, are suffering from the placebo effect, they might see a 5% reduction in attenuation if its torrential rain, not near enough to prevent rain fade, remember the product claims to SOLVE rainfade, I'm sorry, but no way.
Here is some site which describe what rain fade is and how it is caused, not one single part of any of these sites [1] even remotly states that rain on the surface of the dish has anything to do whatsoever with rain fade, with the exception of the sites which SELL product that purports to have a product that does [2], I don't blame them, gotta make money, but the fact is, it's fake, and I will never concede this stuff would have any noticable effect on rain fade whatsoever.
[1] Links supporting the fact that rainfade is caused by conditions in the atmosphere, not the dish itself:
http://www.solidsignal.com/satellite/rain_fade_about.asp
http://www.thefixchicks.com/2005/11/02/satellite-rain-fade/
http://www.telesat.ca/satellites/transmissions/rain-attenuation.htm
http://www.skycasters.com/satellite-internet-service-specs/system-reliability.html
http://www.dbsinstall.com/Help/signalloss-1.htm
Even NASA, which uses ACTS adaptive rain-fade compensation protocol to prevent rain fade, if this product SOLVED rainfade, NASA would just by a few gallons of this stuff rather than implementing ACTS, to be fair it DOES point out some effect of a wet dish over a dry dish, but that reduction was ~5% (certainly not enough to _solve_ rainfade), even so, one would not need to shell out 25 bucks to keep your dish dry (and the 5% reduction in attenuation would not be near enough to stop rainfade), if anything it might give you maybe 1 second or 2 of signal (I'm being generous here) before the REAL effect of rainfade make the signal fall below your receivers ability to lock onto the signal:
http://www.grc.nasa.gov/WWW/RT1999/6000/6100acosta.html
[2] Sites which state that water on the dish face can cause rainfade (coincedently, they all sell products for it):
http://www.sadoun.com/Sat/Products/kings-control/Rain-Shield-Fade-Solution.htm
http://www.wx2100.com/faqs.asp
I know there are more links disproving this snake oil, but I simply could not find anyone else who would claim that spraying something on your dish SOLVES (that is what it says in the ads) rain fade.