I'm late to this conversation, but I've been buying and selling on eBay since the beginning of 2000..
Generally speaking with eBay, they will usually side with a buyer in almost every case. If your product was not accurately depicted for the specific condition of your autograph problem, I would believe eBay will ultimately side with you no matter what.
Unless your seller/trader has a serious attitude, I would think that you can work things out with them such that you don't have to involve eBay in a dispute.
Not for sports cards, but with both a couple complete vintage motorcycle auctions and a couple situations where I was selling something I have had members create a dispute with me, and I've created a dispute with them. As long as you keep a level head with people, 99% of the people who you deal with on eBay are generally going to be amicable in a situation like this, but if you ask someone nicely to reverse the trade and offer to perhaps pay for the return shipping if he does the same for you, I would think the problem can be resolved easily.
Just remember, you get more with sugar then you do with <insert S word for poop here>. If you start flaming the person on eBay you're working with, chances are they're going to dig their heals in the sand and bark right back at you, but if you approach an issue like this politely, I'll bet they come around...