Upload & Sell: Off
The box and ideally the "mint condition" provides the illusion that
item is virtually new with the same thrill one gets when opening
a shipment of new item(s) from Amazon, BH, etc.
Not having a box is certainly not a show stopper, but it does in someway speak to the chances that the equipment is what it seems. For instance, a body or lens that has been through multiple owners is not likely to have a box and all the original accessories with it. If I'm going to buy a 2 or 3 thousand dollar camera or lens I want to reduce the risk as much as possible. Anything that points to it being well cared for is a plus. It is not a tell all of good condition just one item of many that can put the buyer at ease with an expensive purchase from an unknown individual.
What amazes me the most is people who post pictures of equipment that are out of focus, underexposed etc...basically a terrible presentation and then don't understand why someone won't pay their price.