Item and gold trades in Diablo III are handled through a secure trade window. Before a trade is completed, both players will need to click Approve. Because trades require the consent of both players, it is up to those players to make absolutely sure that the trade is correct before clicking the approve button.
Right. Blizzard has introduced the trade window exactly for this reason (prevent scams). You phrase it a bit provocatively, but Blizzard can't prevent (sorry for being so direct) stupidity. You wouldn't take 15k bucks to some dark alley to buy a new char either, wouldn't you?
We had this website pop up several times. There is no means of checking and verifying entries. Someone can just go to this website, put some scam report for your battle tag on there and you have no way to defend yourself.
=> You can probably use another way to contact Blizzard (sending an email, or maybe using the "report player harassment" option or so). Don't know. But unfortunately 99% of all scams are only happening because players are greedy, think they are smarter than everyone else and by getting an item through an in-game trade rather than the AH they can save a lot of money.