Hi;
I may be worrying prematurely but when my handheld scans it stops at a 
carrier that happens to be on one of the common local repeater frequencies. 
When the repeater is in use it overrides whatever else is on that frequency. 
At a prior qth ten years ago I got into most everything on cable or not. 
The theory at the time was that there must have been some type of cable leak 
allowing rf in and cable hash out.  Supposedly if you tune to a frequency on 
2 meters (145.??) you will hear a strong signal if there are cable issues. 
I can't remember the specific frequency and never did find out if this was 
all rumor or if there was some real truth to things.  If anyone has some 
insight I'd be curious.
Richard