This is what I have discovered as far as WNC is concerned.
Most the time they talk in the clear. When they are ready to go encrypted, they flip a switch on their radios. Then it is game over when it comes to monitoring.
I don't know which talkgroups that they use encryption on and which they don't, because I don't have them stored in my scanner. This is because I thought they used full time encryption (because of what is in the database) but I monitor in search mode so when they are talking I still get them.
They also use the analog Event channels a lot, especially when they are doing multi-agency operations, in fact hearing something going on right now around the AVL area, although I'm not in AVL. The only thing I can guess is that someone must have a radio parked on that Event talkgroup on the tower that I'm monitoring.
I've heard SBI here in Rowan County on both the Faith Mountain and Salisbury (Troop E HQ) sites on a number of occasions, matter of fact more times than not, running in the clear. It was what what some of us would consider to be "operational traffic" but nothing that seemed to be of a sensitive nature.
In my 396XT I've made it a point for the agencies I monitor on VIPER to add all talkgroups for that agency, encrypted or not, simply because you never know what you will hear on a day to day basis. Of course that's me, but it's served me well.
On a note dealing with Low Band VHF, Hi Band VHF, and UHF in NC........ Though yes we know majority of our state stuff has moved a lot to VIPER you still never know what you may hear. In my Low Band, VHF Hi, and UHF stuff I have those things programmed as well just because you never know what or who you may hear. But there again, that's just me and what works for me