I have an "Intelligent Human Turing Test" when I sell things on Craigslist (usually professional/pro-sumer music/audio equipment). If someone doesn't pass it I don't respond. If they do they are generally thrilled to be getting a real deal on gear that's in the shape it's been described. This has worked in the greater SF Bay area through good and bad economic times over the last 20+ years.

"In person, cash transactions ONLY, no shipping or trades. Scammers will be ignored. Prices are firm, please don't respond if you don't understand what that means - I monitor markets daily on (CL, eBay, Reverb, XYZ music sites), here are links to recent similar condition gear sold for $xxx more. Respond with a phone # and 2-3 times this week that work for you to talk or meet."

At my work some of our best employees (including myself!) were found through Craigslist. And as a hiring manager, CL ofter brings me better applicants than Zip Recruiter, Indeed, Idealist and other "mass application spam cannons" HR inexplicably favors that have made being a hiring manager a real PITA in the last 5 years.