If you have been scammed in the game you should have sent in an abuse report at the time of the incident, allowing Jagex to have the evidence needed, from their own systems, to take action against that person.
You cannot accuse other players (or clans) by name on the Forums, as there is no way to provide the necessary evidence here. Links to outside sites are not permitted, as Jagex can only vouch for the safety of their own content. Screenshots and videos are not usually accepted as evidence, as they are easily manipulated and edited. Accusations on the Forums become one player's word against another.
For advice on how to spot scams, please see the Support Centre article on
Scamming Prevention Guide
. The old saying, "If it seems too good to be true, it probably is" is good advice in dealing with others in RuneScape as well as the real world.