I've known a couple of scanning enthusiasts in OKC that like their Spectras very much. Since I drive an SUV and like to park in my garage at home, I generally limit my scanner antenna to the Antennex tri-band scanner antenna but I do occasionally use a larger custom concoction that has an NMO base. However, I can reliably report that I've received low band OHP transmissions using just a VHF-Hi 1/4 wave magmount and it also received 800 TRS just fine, too. Outside of the cost, antenna experimentation is part of the interest in the hobby for me.
As to your grounding question, I think you are giving yourself a clue about the need for grounding with your comment regarding "crap static". I'd recommend you do some reading on the subject on the following excellent website: http://www.k0bg.com/
It is oriented to the mobile ham but you can learn a lot about mobile operations and installs for even scanning. Alan is also really good about answering questions on eham.net and QRZ.com on the mobile operations forums on those sites.
Electrical grounding and RF grounding are definitely two different things. Electrical grounding creates the flow of electrons to power your system. In a transceiver set-up rather than just a scanner, poor RF grounding can cause the transmitted RF energy to flow in undesired ways by returning on the outside of the coax to get back to the radio. In both transmitting and receiving, RF grounding is part of the antenna system to ensure the RF signal is used to its best advantage in the system.