On a more general point, all TV antennas will receive some amount of signal from all directions. Some are very directional, meaning they receive quite well from one direction and far less in most other directions. Some antennas are designed to have nearly equal gain in all directions, which almost always means that they will not have much gain in any one direction. It's always a trade off.
The Antennas Direct, Winegard, Antennacraft & Channel Master product are documented fairly well, making it possible to sit down, do some math and estimating that results in a well educated estimate of what you can expect from the installed product.
Here are the engineering data sheets for the DB4e, C5 & HD7082P:
http://www.antennasdirect.com/cmss_f...y/DB4E-TDS.pdf
http://www.antennasdirect.com/cmss_f...20with_uhf.pdf
http://www.winegarddirect.com/pdf/spec_HD7082P.pdf
Here are examples of how to relate the antenna performance and TV Fool report numbers:
http://forum.tvfool.com/showthread.php?t=109