Remember that the database is crowd-sourced, meaning it depends on hobbyists and listeners to submit updates to keep it accurate and complete. It's certainly possible that all LE communications in Anderson County are encrypted and it just hasn't been noted in the database yet. I'd be a little surprised if the muni PDs encrypted, but it's certainly possible.
One minor downside to Uniden scanners is that they completely skip over encrypted radio traffic. So you'll never know for sure if it's encryption or not, you just won't hear (or see) the transmissions.
Since Fire, EMS, SCHP and other agencies are not encrypted, you should be hearing those regularly. If you're not, then you may have a programming issue, or a reception issue.
Service types (aka "TAGS" that someone else referenced) also need to be enabled for the services you're interested in hearing. If you only have Law Enforcement tags enabled, then it stands to reason why your scanner might seem quiet. By default, consider enabling all service types until you're sure you're successfully monitoring the Palmetto 800 trunked system, then disable the service types for those that you aren't interested in.
Consider adjacent counties. Depending on which "side" of Anderson County you live on, you can hear a lot of activity in Greenville County on the Palmetto 800 system. Laurens County also uses Palmetto 800. If that's of interest, you'll want to program (and be able to receive) the sites in those counties. The Anderson site might carry some traffic from those counties some of the time, but not all channels and not likely all of the time.
With the NXDN license, you'll be able to monitor the Fleettalk system which is now used by Pickens County public safety agencies. And so far, there's not a lot of encryption for them. I think it's also used by Abbeville County (someone correct me if I'm wrong) but it looks like their primary LE channels are encrypted. With the DMR license, you might be able to monitor activity in Oconee County. I see Oconee Co EMS is now on Fleettalk but is encrypted. I'm sure there are plenty of other things to monitor public-safety wise, but you may need to invest in a better antenna system.
The fighter jet testing out of Donaldson is something that interests me also. Maybe someone else can help explain how to listen to them. I don't think Donaldson has an active tower, so flights from there might talk with GSP airport TRACON on their frequencies. I'm not sure how high they typically get, but maybe they also talk to Atlanta Center on the Owing sector frequency, maybe others? I would guess that they have some "internal" channels, but I'm not sure how one might go about finding those other than dedicated searching. License WQQK529 might hold some clues.
I will read through your link and be sure to try some new searches.
