It depends on who it came from. It's worth it if it's someone I know that needs the cash...it would be a win-win because for me I buy a ton of Coach, and for them, they need the cash...although they take a slight hit. If it's on Ebay, then I know some of those have been scams, so I would consider that very carefully.
If I were buying Coach and I knew the source I would.. I have sold a few gift cards in the past when I needed the money more than the bag.. I took a hit but I got the cash I needed and the buyer got the bag at a discount.. win/win.
I have actually pondered doing this lately and I may still. There are some items I have in my collection that I could live without but were purchased with store credit so I cant return for cash. If I took them all back to the store, got another store credit all put on one card I could sell it, take a slight hit but still have cash for something else.
Maybe that is what your source is doing?
If you can use it and it's a trusted source, totally do it, but only if you would spent the bucks at Coach anyway. Would be especially cool if you were going to buy something with PCE -you'd get the discounted gift card and then get the 25% PCE - would be a nice savings on something!