I think Craigslist is a perfectly acceptable way for someone to try to find a new home for a pet they can not keep, or for a potential owner to find a new pet to adopt.
But there are two things to consider here...
1) This site (
GPC) is pro-rescue, anti-breeding. Most of the members here feel strongly about this and want to save animal lives by reducing back yard breeding, and promoting adoption. Flagging craigslist ads is one way of doing this. If the BYBs can not get rid of their "stock" they will stop breeding!
2) No one here is deliberately flagging legitimate ads. The rules of Craigslist specifically state under their list of prohibited items "Household pets of any kind... Rehoming with a small adoption fee OK"
In other words the values on CL are the same as on here - rehoming animals is fine, selling animals is bad.
Of course, in some cases it is difficult to tell, but every breeder ad removed is one step in stopping byb's and reducing overpopulation!