When you do a search on craigslist you pick the section of the site you want to search (i.e. "Furniture", "Computers", "Cars/Trucks", "Free", etc...). Based on my experience, the "Free" section is almost always not worth the effort. Either the items are low quality or they are impossible to get due to craigslist "flippers".

So I could see a situation where most buyers with actual intent to purchase are only searching in the "Furniture" section. And the chairs in question might not have been nice enough to attract interest from the "flippers" in the free section.

It's pricing theory (there's a better name for it ... but I cannot recall of the top of my head)

Underpricing something is as bad (or worse) than overpricing it

If I think that chair is worth $50, and you're giving it away ... I think there's something wrong

If I think it's worth $50, and you ask $20 ... I think "he must not want it - this is a great deal!"