If it has the Gibson headstock and/or logo it is illegal to sell - even if the seller says it is a replica.
You should report each and every ad you see and get the guy shut down. Stop someone else from getting ripped off somewhere down the line (it does happen).
We have a thread for alerting our own members to fakes here:
http://www.guitarforum.co.za/special-offers/gumtree-fraud-warning/