Seems like the Steam version of Farcry3 has been patched. As what he told.

DmC on Steam has been patched, but when you press F1 the trainer works, until you press continue, or going into any of the options.

Sleeping Dogs, I don't know what he's talking about, the latest trainer still works for me, not sure... unless I didnt get the patch yet, but it still works for me.