Hi all,
While some swear by glass mount antennas most swear AT them even when the "sweet spot" is found with an SWR meter or antenna analyzer. Basically they're a troublesome lot for a whole plethora of technical reasons and a receive only setup leaves you guessing what they are. If that's your only option you have only one choice, live with them or live without a mobile scanner.
As for the VHF Lo Band reception problem, it's common to ALL mobile antennas not specifically made for that band. That's because it's the "forgotten band", when you try to resonate an antenna on so many bands sumpin's gotta give and that's the longest element. Since a quarter wave is about 70 inches long it's easy to see why and if a shortened "base load" is used it becomes a monoband antenna. There are limits to everything and there you have it in a nut shell.