Used item sales on eBay are incredibly diverse. People sell everything from used clothing to used computers to used antique furniture to used cars and homes on eBay, and the way in which you present your item can have a great deal to do with its marketability and (if you're selling via auction format listing) ultimate sale price.
Apart from taking a nice assortment of high-quality photos for your listing, perhaps no aspect of presentation affects the sellability or marketability of an item more than the way in which you clean (or don't clean) it before taking these photos.
Here are some things to keep in mind about your cleaning practices for eBay selling.
Know the Market Value of the Item Before Cleaning
Do a search for completed items or use a service like Terapeak to know the used sale value of your item on eBay before deciding how much time and money to spend on cleaning. This will help you decide how much elbow grease or cleaning expenses are justified by the value of the item you're selling.
Clean Most Items that can be Cleaned for Free
In most cases, if you can clean an item yourself with materials on hand before taking photos, doing so will improve your sales performance. Things like clothes, consumer electronics, household items, outdoor sporting and yard equipment, and so on, all benefit from a good cleaning before photographing.
Don't Be Lazy with Your Cleaning
Many mass-produced consumer goods have nooks and crannies and textured surfaces that can retain dirt and discoloration unless you actually spend the time to get into these crevices with whatever tools are available to you. If it's a difference of minutes, do a thorough job. Get the discoloration out of the cracks if you can, even if it will take an extra 10 or 20 minutes unless the potential value of the item doesn't justify it.
Consult an Expert Before Cleaning Antiques or Collectibles
Many items of this kind actually lose value if or when you clean them, so before embarking on a cleaning project of a vintage, antique, or collectible item or items, consult an expert about how a cleaning might affect its value and what kind of cleaning is appropriate.
Go the Extra Mile for Vehicles and Real Estate
In most cases, the value of these items justifies a serious "cleaning," which may include things like a good wax and polish/shine (for vehicles) or even things like a yard overhaul and a paint job (for real estate).
Use Appropriate Chemicals for Consumer Electronics
Clean screens with water or specially-made screen cleaners, since window cleaner, ammonia, or other common household cleaners can actually damage consumer electronics screens and other surfaces.
Clean Yellowed or Discolored Plastics in Hydrogen Peroxide
Electronics enthusiasts were the first to discover that white or beige plastic items that had become discolored by exposure to the sun could be restored by soaking them in a solution of hydrogen peroxide for several days (or, even more completely restored by using a slightly more complex, but still inexpensive, solution).
Do a Little Research About Cleaning Items of Your Yype
If you're cleaning a fairly used or soiled item of a kind you haven't cleaned before, do a two-minute Google search to see how enthusiasts or users of this kind of item clean it. This can help you to avoid spending hours when there's a five-minute method that works well.
Never Clean in a Way that may Create Liability for You
Only clean with harsh or dangerous chemicals if you're willing to do what it takes to be absolutely sure that every last bit of residue is gone from the item before you ship/sell. Otherwise, your risking returns or worse when the buyer receives the item.
Use a Professional Cleaner if Appropriate
If justified by the value of the item, the use of a professional or expert cleaner or cleaning service can be justified; just remember not to spend more on cleaning than can be recovered with a sale at fair market value (taking into account the "take" you'd like as well).
Know How to "Photograph Clean" Rather than "Photograph Dirty" for Selling
An item must do more than be clean to achieve good sales performance; it must also appear clean in your item listing photos. Very clean items can be made to appear very dirty with bad photography techniques. For black, brown, or dark-colored items, avoid direct sunlight, high-intensity light (like flashes), and regular (automatic) camera exposures. These will tend to make the item look "dirty" and worn by lightening the natural color considerably and highlighting dust particles and surface blemishes. Instead, use indirect, diffused light and reduce exposure until the black, brown, or dark colors look true. For white, beige, or light-colored items, do the opposite and shoot with very bright, high-intensity light while slightly overexposing. For shooting items with bright colors, consider setting your camera to a "vivid" mode or using an image editor like photoshop to increase color "saturation."
Talk About Cleaning in Your Item Sescription
If the item has undergone a thorough cleaning or even more if it has undergone a professional cleaning, be sure to mention this in your item description. "Item is used" has a very different ring to it than "Item is used but has undergone a thorough professional-style cleaning."
Sell Your Cleaning Experience and Practices
If you clean every item that you sell, you're likely someone that knows about cleaning items well, and a higher-quality seller to boot. Use that in your listings by saying "We thoroughly disassemble and clean every item in our inventory. We only sell it once it's spotless and looks fabulous in person."
Turn a Non-Cleaning into a Selling Point as well
Even if you decide not to clean an item, turn that to your marketing advantage with listing points like "This item could probably use some cleaning and TLC that we haven't bothered to do—which is why you're going to get a fabulous deal on it."