I also use a "whip" dipole, the one made by Magnum Dynalab, up on the roof of my house. When we tested various antennae, this one sounded much better and had much better reception than the bigger array-type antenna that we also tried and that I assumed would be the best. Anyway, when the whip antenna was actually mounted, there was terrible reception! It turned out that it was mounted too close to the metal gutter and the gutter badly interfered, just like Sean said. So we curved the whip out from the house, away from the gutter and other trim, and reception was great. The antenna now does not point straight up to reach its highest point, but instead points sort of diagonally up and out from the house. So yes, the fascia etc. can be a big problem. But if you are listening and you don't hear static and noise, then you seem to be okay.
FM antennae question
I am using the Fanfare FM-2G dipole antennae and I just had my brother move it to the peak of my roof; it is attached to the gable end fascia. I have very large fascia, he mounted the antennae to the lower part of the fascia so the first six inches of the antennae is against the fascia before extending past the roof. Could this cause any performance loss or am I going overboard here???