If one joins the Campfire to share, participate, learn from others and has stuff he/she no longer needs and posts it in the Classifieds is one thing... not a problem at all...
But for someone to join the Campfire for the sole purpose of selling flea market, gun show, trinkets, and flipping scrounged up junk, then that a horse of a different color... not unlike the compass sale being discussed in the Hunter's Campfire as we chat now.
There are thieves working the Classifieds right now...