Cable amps are going to be optimized for lowest intermodulation distortion, the noise figure, which the ability to hear very weak signals will be a lower consideration in a cable TV system.. Also in a cable TV system, all of the signals are at the same relative level which controls intermodulation effects. However, when you monitor off the air the strong signals from paging transmitters, NOAA weather , FM and TV broadcast, will overwhelm a wideband amplifier and the preamplifier of your scanner receiver. Intermodulation will ensue.
If I were trying to receive satellite signals or moon bounce I would want 0.5 dB noise figure or less, and I would have a filter to prevent out of band signals from reaching the preamplifier.
