I think you must be new to buying and selling online.

Trading Post, like eBay, Oztion and the vast number of online auction sites around the world provide a place where buyers and sellers meet.
None of the sites offer a fool proof or scam proof system of connecting buyers and sellers.

Likewise none of them offer to "support" their ads, they simply provide a place where buyers and sellers meet.

All the sites state this quite clearly in their Terms and Conditions section and warn buyers to be careful when buying online.

You haven't explained how you were scammed, just that the "Ad" scammed you, which of course isn't accurate as the Seller that placed the Ad is the one at fault, not the Ad.

If you were scammed I'd be interested to know what the Ad said and also how you paid the money to the seller.

Cheers
Bruce