This scam is similar to the outdated Password Scam where a scammer would say "Hey Jagex blocks your password see: ******". Well an update was made so that this would actually happen but any slight variations such as putting full stops in would allow it to go through. This is the basis of this scam. The scammer will usually have another internet window open to change the victims password once they find out what it is, this way the next time the victim logs out the password will be reset and the scammer can acess the account. There is a chance that you can recover your account by using your recovery questions on Jagex's "recover a lost account" page.
The Actual ScamEdit
Like the old password scam the scammer does still say a similar thing but it says "Hey Jagex blocks your password if its backwards see: ****". So a victim would simply type in their password backwards and it would appear such causing the scammer to get their victims password.
However thwarting this scam is quite easy: simply ask "Why in the world would anyone want to type their password backwards? It's pointless." This is why this scam isn't very effective: there's no point at all in seeing if your password will be blocked. Why take the chance? Or a player could type a false password so they would end up wasting the scammer's time when they tried to gain access to the player's account.
Example of being scammed:
Scammer:hey look jagex blocks your password if its backwards see ******
Victim(s):cool let me try! drowssap.
Scammer: (ussualy insults victim(s)) Noobs
victim reports scammer for password scamming