Item Scamming is a common form of scam in RuneScape in which the scammer unfairly deceives victims to obtain valuable items or large amounts of coins for little or nothing in return. Under the Rules of Conduct, this violates the 'Scamming' subsection of Honour, and Jagex will issue various punishments to players caught item scamming, depending on the degree of the scam.
Many famous scams are for armor and money. Remember, if a deal is too good to be true, it probably isn't a good deal at all.
The two major scams, however, remain item switching and money quantities. Item switching consists of putting a great item, and at the last moment switching it with a worthless one looking like it. The second method is simply to use leet (100k becomes 1004) or to mess up with 0s (10k for 100k). However if someone puts 0s less than the expected price maybe they are just mistaken.
In any case, those scams are less likely to happen since JaGex's wise decision of flashing edited items or money. Also, large amounts of money are now different colours, so if someone changes 100k gold to 1004 gold, it will change the colour from white to yellow, making the change more easily noticeable.