Assuming a merchant accept Bitcoin,
You as a shopper, place an order, and that merchant did not deliver, or sent to the wrong address, or sent a fake product.
You can not reverse the payment, you can get your bitcoins back, and the only thing you can do it leave a negative feedback.
Of course, there are many other scenarios, like phishing websites, fake websites, selective scams, and so on
What are your thoughts and ideas to prevent these scams.
As you can see now a many are fraudsters they want to get a easy money. The one thing you do don't trust anyone and best thing is don't buy online using bitcoin. You can cash out your bitcoin in real money then go to buy the things you want.
What the Internet don't buy things for other currencies? Scammers do not pay attention to the currency. It does not matter what currency you have selected. On the Internet you need to buy only in the checked areas.