It is true that a large percentage of radar problems are actually problems in the radome. Whoever posted that note that "only moving water" paints is wrong.
Best source is Capt Dave Gwinn. Knows radar better than anybody from an operator standpoint, teaches seminars, etc. Don't waste your time with Archie Trammel unless you're only interested in applying the ideas to light airplanes.
Go to the Honeywell web site and do a search for Gwinn and you'll find him. I'm sure you can get information through them.