The four spurious products in the file are due to internal mixing products and undesired interactions of the mixer, amplifier, and oscillator stages. They are quite prolific, actually, in GRE models! I know this to be a fact from both personal experience as well as those reported by others. I have done a fair amount of work in this.
Not all products will generate spurious responses in passbands as selected by the receiver when tuned which will cause immediate in-band issues. But some will. There are MANY variables.
This file is by no means exhaustive. To do so, you would have to know more details of the design and do a very exhaustive analysis of non-linear mixing products. Usually, in a lab, of course, we do quite a lot of in-circuit "sniffing" and present many different potential interferers to the inputs and measure the responses. But we have to start with the main usual culprits which include 1/2IF and images. Then we look at intermodulation first by analyzing the 3rd order intercept and P1dB of the dominate elements in the chain; typically we look at those qualities in the amplifiers as well as in the mixers which can get nasty to work with!
But the spurious elements I have noted in the worksheet are indeed quite prevalent and extremely valid, I assure you!
Do you know why GRE changed their 700MHz coverage with later firmware to cut out the 782MHz to 791MHz portion of the band? Plug in 785MHz into the worksheet and check out the third harmonic of the first LO spurious and see what that frequency is! Yes, right in the middle of the mobile portion of the cellular phone US AMPS band - not really important due to both the nature of the signals used now as well as the fact that that is the mobile portion BUT they had to comply with the FCC requirement to not receive those frequencies and this was a severe weak point in their design. I can absolutely guarantee you that I can readily spot many spurious of this kind from 800MHz trunked control channels and voice frequencies in the upper end of the 700MHz band - with just my rubber ducky whip on the handheld. The calculator in the sheet nails these exactly. The same goes for the 900MHz pager signals appearing in the federal portion of the VHF-HI band - I can nail those too and repeatedly call them up and experience them - it causes problems for monitoring some federal USFS frequencies where I live. The problem is, contrary to your statement that "...many of the spurious response frequencies are well outside of the front end bandpass filter response curves and in many cases, even outside of the LMR/Broadcast bands..." these, in fact, DO cause in-band problems and much confusion to unknowing users! The scanner is designed to receive many of the frequencies that these spurious issues fall on and these will often cause problems on completely disparate bands - what you are faced with when using a very wideband receiver designed with too many cost cutting measures in the RF and IF sections.
You also state "...a much bigger problem is that of in-band interference caused by inter-modulation products emanating from the scanner's pre-amps and mixers." Well, guess what that 460MHz stuff appearing in the 417MHz range IS?! That's right - intermodulation products stemming from unintentional radiations and mixing products from the radio's internal mixers and oscillators (and maybe pre-amps, too)! In fact, that 800MHz stuff appearing in the 700MHz band is pretty much "in-band".
The only one I have yet to experience personally is the 1/2IF problem as the design limits that way outside of most strong signal areas in most tuning cases. But you'd be surprised by how common the other three insidious demons are in these scanners!!
I get that there are many other interferer potentials, of course, but again, trying to document all of them really requires much more intimate knowledge of the design of the receiver, the layout of the pcb, the parts used, the shields and case design, etc. as well as real lab equipment to verify and test it all (and find the ones the initial analysis didn't get!).
By and large, you are "preaching to the choir" with me, as I think you realize. I agree on the RF designs of these scanners being somewhat underwhelming to say the least. But this is what most of us must deal with; I felt tools to help non-technical folks understand why they receive "weird stuff that isn't really there" would be useful.
I am intending this to be a quick and useful tool for testing four likely possibilities when picking up "something weird" that seems like it shouldn't be where it is.
Anyway, I have also created a version of the file that uses the Open Document Spreadsheet format (.ods) which can be used with the free LibreOffice Calc program for those who cannot afford or don't have Microsoft Excel 2007 or later. I have attached it with this post. For those who don't know, LibreOffice can be found here: Home | LibreOffice - Free Office Suite - Fun Project - Fantastic People