SHOP TALK : Best to Take Mattress Purchases Lying Down : Manufacturers sometimes give confusing information. Smart consumers will put prospective buys to the test.

We may love to shop, and we may love to hunt for bargains. But shopping for a new mattress is never any fun. One key reason for this is that you never know whether you’ve found a real bargain.

Here’s a look at why buying a mattress set is such a miserable experience--and a list of tips on finding a bed you like without losing sleep over it.

Retailers call a mattress and box spring a “blind item.” In other words, we can’t see what we’re buying. Here’s why:

Manufacturers and retailers have made price comparison impossible by giving different names to nearly identical mattresses sold at different stores. A Simmons Beautyrest Horizon at the Broadway may be called a Simmons Beautyrest Ambassador at Bullocks--and still another name at another outlet. The mattress will be identical in structure, but the ticking or upholstery will be a different color or pattern.

Making matters worse, the manufacturer’s label, whether the model is low-end or high-priced, never answers questions about quality.

The temptation, then, is to turn to the warranty. And most mattresses have impressive warranties. But here again, quality is difficult to assess.

Long-term warranties--some are for 15 and 20 years--often specifically limit liability to structural failure, like a popped spring or loosed stitching in the main case. All of which means that the valley you and your mate have put into the mattress through years of use may not be covered. The practical life of a mattress, industry experts agree, is really eight to 10 years’ use.

Then there is the jargon. Ask for a “firm” mattress, and learn that all mattresses are called firm. Or super-firm, ultra-firm or ortho-firm. We didn’t see a single mattress called “Soft” or “Super-Squishy.”

The trend in mattresses now is for a “plush” bed surface, more padding for more comfort. Many of the most expensive mattresses were the “pillow-top” style. These thicker, plusher mattresses feel great but will probably require new bedding. Only sheets described as “deep-cut” or “high-contour” will fit these fat mattresses.

How, then, to find the right bed?

In the absence of comparable ratings and standards and meaningful warranties, the real guide is comfort and price. To shop well for a mattress, you must try it out!

Dress comfortably and be prepared to look like an idiot. The only way you’re going to know if the bed is right for you is by laying down on it for a few minutes. Roll around. Bring your partner, because a bed that is comfortable for a 110-pound woman may not be comfortable for a 200-pound man or, for that matter, both of you at once.

A word about the box springs. They are comparable to the shock absorbers in your car. It is not recommended to put a new mattress on an old box spring. This will cause the mattress to wear out fast. Still, a new mismatched mattress/box spring set may be a way to get a good deal. Just be sure the mattress and box spring are mismatched only in cosmetics, that they appear to be of similar quality.

Now go for price. You’ve found the right mattress, with comfort as your guide. Old-fashioned bargaining is in order. Hesitate, and see if the sales person can lower the price. If the mattress isn’t on sale now it most likely will be next month.

Ask if there are any close-outs or discontinued mattress sets. The bigger the store the better the chances are they will have some of these. Savings can be substantial.

And remember that a bed frame can usually be included, free of charge, with the purchase of a new mattress set. Make sure delivery, set-up of the new bed and the removal of your old mattress are included, too. Since so many things with mattresses are vague, most things involving mattresses are negotiable.

Julie Sawyer, an experienced shopper, writes the Shop Talk column regularly in Ventura Life. Want to know where to find the best stuff at the best price? Write to her at 5200 Valentine Road, Suite 140, Ventura, 93003 or send faxes to 658-5576.