I'm sure what you say is true, that there area a lot of scammers out there, but the site must also have real genuine sellers there as well. And also some products lend themselves to scamming more than others, laptops as you say being one, and other consumer electronics, ipods, psp's etc.
Perhaps its just a matter of doing due diligence, such as asking for all contact information, phone number and website etc. And perhaps also asking for a sample before you buy the product in full. Because most scammers would not have the products at all.