Before I pull the trigger on a 675.00 Uniden SDS100 scanner does anyone really know if they will work in Salt Lake city?
Before you spend any $$ has anyone assisted you in fully understanding what your issue may be and how to possibly address it.
My recommendation is only "if" your scanner is used in a stationary situation. i.e. on desk at home.
A simulcast radio system is a network where multiple transmitters from more than one transmitter site broadcast the same signal simultaneously on the same frequency. The garble you hear usually is where your radio is receiving more than one site and they are canceling out each other. The best test in this situation I refer to as "Less is More" one would think that best antenna to hear the most signal is the solution when indeed its not at times. My recommendation is also with the consideration that you are only monitoring the Simulcast system.
Remove the antenna when receiving a signal to see if you can still hear (without it). If not you should try a lesser antenna. Example could be a paperclip or short wire that can be inserted (Don't force or damage the connector). You could purchase an attenuator that lessens the signal strength.
EXAMPLE
(https://www.amazon.com/Acxico-Coaxi...ix=bnc+att,aps,102&sr=8-25&xpid=2amP0B33gWx7p)
Goal is if you can remove the reception of the offending other sites you will be able to hear clear as a bell.
That said by performing these steps you may render the scanner unable to hear other systems or radio services because they require the additional antenna gain. The SDS-100 and SDS-200 are known for their ability to process and selectively monitor simulcast systems but as you noted it indeed comes at a cost. Personally I have both TRX1, TRX2, Many GRECOM, Uniden versions and am able to monitor my area Simulcast systems but it does require additional adjustment and dedicating the radios(s) to a single service. For general All Systems scanning and mobile scanning I use the SDS-100 with additional GPS that automatically selects the transmitters specific to my geographic area at any given time. My daily commute is ~ 1 hour and I pass through 3-4 counties all of which have differing configurations.
End of day you should decide what you wish to listen to and how you will use your device (Mobile or fixed) and configure/purchase accordingly.