Check out FotoFuze - a cool FREE service you can use to remove ugly backgrounds from your photos. Remember, the only thing between you and your potential buyers is a computer screen. You must do everything possible to get them to your listings, then to buy your items. Mediocre, or even worse, poor photos are a huge turn-off for buyers. If photos are sloppy, they may think shipping and customer service is going to be sloppy, too. Presentation is everything on eBay.
Here is a photo I edited recently - sometimes blues and purples pull too much yellow into the images where I do my photography, and this tool will correct that in about 2 minutes.
It takes a little while to get the hang of it, but it sure helps photos look better. At least give it a try to see if you like it or if it works for you. I don't use it all the time, just when needed.