They collect your personal Information organizing product demo at Malls collect unsuspecting peoples contact details by asking them fill form to win contest. Next your Mobile e-mail is bombarded with spam mails with offers and contest.
In contest promises to win gadgets like iPhones for mere 100 rupees otherwise you can shop with your money. But after sometime your money just disappears. You will be not replied in any manner. No phone, no email no contact address.
Just big scam.