Related, so many sellers are now “pro” sellers like what happened to eBay. Keyword stuffing, prices that are comparable to sale prices of new, constant automated reposting, etc.
And not hidden and tucked away either: it's the absolutely very first top-most set of options on the search results page. See those three [all] [owner] [dealer] buttons? Click "owner". You're welcome.
Whenever I'm buying something on CL, like say a car, I always ask the person who answers the phone: "I'm calling about the car. Tell me X about it."
If they reply "Which car?" then you've reached a dealer, not an owner.