Cost of returning a "free shipping" eBay item

[Acer]

gadje wrote:
Because the seller assumes he would make a sale and is willing to absorb the cost of shipping. If the sale does not happen the seller loses money.

And the seller assumes the risk of losing the cost of shipping when the item is returned. Free shipping is a marketing tactic intended to increase sales, so on the whole the seller should come out ahead...IF they have a good product not prone to returns.