Each regional office is different but out here the majority is coded. Sometimes you'll hear in the clear but it's normally radio checks or whatever.
A nearby area has a lot more in the clear like where the SA is going, leaving, etc and license plat/DL checks.
I have yet to hear an operation. The local repeaters are so screwed up they key-up from noise or screwed up console links. You normally end up locking them out. I know of one that's broken yet they don't even know.