We have the ability in the system to enable you to set item conditions for products you sell. To enable this feature, once you are logged into the system, in the blue bar, click on the gear-shaped button on the far right and go to Settings > Website Settings > Products, and you'll see an option for Item Condition about half way down the list. Set it to On and then scroll to the bottom of the page and click Save. Now in each of your products, you will have a drop-list on the main product info tab below the price areas where you can set the item's condition. If you make changes to that field, be sure to scroll to the bottom and click to Save the product.
You can find comprehensive information about how to set up and work with Item Conditions for standard and for serialized inventory by clicking here.