Your right, it is the million dollar question that many of us have spent a long time trying chase down and answer.
Here is a small chunk of MY 2M satnogs station spectrum…
Yours will be very different.
Depending on the downlink frequency of the satellite that I (or fredy) schedule, the pattern of terrestrial noise will be very very different.
This is why I use SDR# or some other program to see the typical signals on the 2m and 70cm bands about once a month or so and make sure nothing has popped up unexpectedly.
So, in short, you will find patterns for each satellite. Once you know what you are up against, you can start to try and filter it and deal with it.
Hope that helps.