Well they may work to keep the stuff off the LNB eye, but what do you do about the ton of rain/snow/sleet/cows between you and the satellite?
We broadcasters have tried everything, we found the best bet to keep the signals coming was to go to bigger dishes, in heavy snow areas heated radomes were used, but when the clouds are chock full of heavy rain/snow or other things a bigger dish comes in handy.
But not much can be done when you get total signal blockage due to too much moisture between you and the satellite on a "Ku" band dish/LNB, this is why we went to "C" band, less signal loss on the lower frequency's due to water vapor.
One way I keep the snow/ice off my dish is to use a black heavy gauge lawn/leaf bag, slip it over the dish and stick a drop light in it with a 40 watt bulb, a temperature sensor for the pipe heating tape works to turn it on when it gets cold enough to freeze, a few tie wraps will close it up.