By Jim Donovan: Misleading discounts, bogus deals, and sales that can cost consumers big bucks. They’re just some of the shopping scams and bum deals recently uncovered by ShopSmart, from Consumer Reports.

In its September 2014 issue ShopSmart, identified common shopping trip-ups and ways to side-step them – below are some examples:

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Misleading Mattress Sales. Some mattress manufacturers require retailers to charge no less than a certain set minimum price. For example, a queen-size Serta Vantage mattress has a minimum price of $1,074. Some retailers said their regular price was much higher, such as US-Mattress.com, which listed the regular price as $2,148, a “savings” of 50 percent. Watch out: Never take the promise of huge savings at face value. Comparison shop for the same or a similar mattress (direct comparisons aren’t always possible and always try to negotiate.

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Penny-Auction Deals. Sites such as DealDash and QuiBids advertise what seem like amazing deals. But those so-called-penny-auction sites can really cost users. Unlike traditional auctions, bidding isn’t free. Bidders buy up front – usually for 60 cents or so each bid. And any bid money spent is gone, regardless of whether or not a shopper wins the bid. The chances of getting big ticket items are extremely low prices are small and users can spend a lot of money trying. Watch out: Think of these sites strictly as entertainment – like gambling – not smart shopping. Or just skip them.

Discounts with a catch. Usually when a store advertises a product discount like two for $6 on sale shoppers can still save if they buy just one. But that’s not always the case. One ShopSmart shopper tried to buy a bottle of Ajax dishwashing liquid based on a three-for-$5 deal, but that one bottle rang up as $2.19 instead of $1.67 at the register. Watch out: Look for any fine print on the sale sign, and watch the cash register.

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For more information visit: www.ShopSmart.org.