These days, it may not be enough to list an item on eBay, Etsy or Amazon and expect it to be seen by shoppers. Your listing competes not only with scores of rival listings, but with promoted listings (paid ads) as well. Do sellers now need to pay to advertise their listings on top of the fees they already pay to list on marketplaces? A report from Kenshoo found that ecommerce ad spending increased 54%…