A used couch might come with plush pillows and questionable cleanness; even your own well-used one possibly seats not just people and pets but germs and allergens. Regardless of where the ick factor or unfavorable smells originated, you might be left wondering how to disinfect the big bacteria-harboring piece -- without damaging it. Use the couch's upholstery type as a guide for disinfecting practices.

A Clean Start

Some couch-disinfecting practices kill germs but don't actually clean the upholstery, or don't do a thorough job. Start by vacuuming the fabric thoroughly, getting down the back, along the arms and in any creases with an upholstery attachment. Doing so provides better or longer-lasting results because much of the problem originates with what's on or embedded in the fibers, such as pet dander, skin cells or food particles.

Spray It Fresh

Disinfectant sprays for hard and soft surfaces offer a quick way to destroy couch germs. Sears suggests using deodorizing spray with enzymes to eliminate upholstery odors. A light mist of oxygen bleach or color-safe bleach diluted with water, according to the labels' recommendations, can sanitize some W code water-safe fabrics.

For S- or SW-code upholstery, use a disinfectant solvent, such dry-foam shampoo, brush-in-style powder or a spray bottle filled with rubbing alcohol -- or vodka -- instead of a water-based mist.

Apply Steam

Don't discount steam -- heated to about 240 degrees Fahrenheit -- to destroy germs or combat a musty smell. Reduce the chance of water damage by using a dry-steam cleaner, passing the upholstery attachment over each section a few times; although the machine uses a small percentage of water to produce vapors, it won't saturate the material. If your couch can handle water and steam cleaners, use a standard steam-cleaning machine and the appropriate shampoo for odors, such as pet urine. If odors linger, allow the fabric to dry, and then mist it with scented spray disinfectant for a more comprehensive job.

Disinfect Leather With Vinegar

Vinegar isn't just a salad-dressing ingredient; it's also a leather-safe germ-fighting, mold-busting, unpleasant-scent-ridding cleaning hero, when you use it appropriately. Dampen a soft, white cloth with a half-water, half-white vinegar solution, and wring it out well. After a good wipe-down, dry the leather with an absorbent towel, getting in the creases and folds.

Sanitizing Slipcovers in the Sun

A slipcover can act as a trusty protector, guarding washable and dry-clean-only or X-code couches alike, but it needs occasional disinfecting itself. Refer to the cover's laundering tag, which may suggest a cold-water wash and low-temperature dryer setting -- neither of which destroys germs. In this case, after laundering it, hang the article in the sun for a few hours, letting the bacteria-blasting rays wash over it before putting it back to work.