@ Jeremy Cheng - Those types of threads (red paperclip), provided they are not begging, have always been allowed on the forums. They are not scamming, because the user is not claiming that the two items are of equal value.
These threads have usually been posted either in the MarketPlace to advertise what they are trading, or in Goals & Achievements, to record the progression. OSRS does not have a separate G&A forum, so G&A type threads are placed in the Old School RuneScape General Forum.