I have heard that they make a paint specifically for asphalt shingles, which they guarantee for 15 to 25 years. Is this a mistake when thinking of re-sale? I've seen various web sites for this stuff, looks OK but I do not want to spend hundreds of dollars, only to find out I've created a ridiculous looking disaster. I am a do-it-yourself homeowner. My roof looks fine to the average person, but I know it is time for a new roof. Roof paint..good idea or bad?