A deal (usually offered by a cable company, or a big box store) that initially may seem beneficial to the buyer, but on further examination, it is realized that the deal really only benefits the seller and the buyer gains nothing.
The most blatant example is a cellphone company offering a brand new cellphone at no price and then price gouging you for months and years to come for the service.
A classic Best Buy/Future Shop Faux-Deal is attempting to offer you an extended warranty for free instead of lower the price of the actual big ticket item in question. Because chances are you won't need the warranty, and you'll walk away paying full price for the item thinking you are a savvy buyer.
A classic internet provider trick will be offering the modem for free when you sign up for their service. Well no effing duh, without the modem there's no way you can get their over-rated price gouging internet connection.