I scored a free Wrath of God the other day. This isn't like a trade toss-in, this was a no-strings-attached "add me to your EDH stack" Wrath of God, and I got it simply because I know how to clean cards. If you can do this too, you can instantly increase the value of older cards like dual lands and Sol Rings.
You've seen them, disgusting-looking cards, usually with a once-white border that is now gunked up. It happens to old cards and people don't want to trade for them because they look like a gunky keyboard from a high school computer lab. Unlike old coins or antique furniture, Magic cards aren't worth more when they retain the dirt and grime from years of play.
They're gross and there's no reason to have cards that look so bad. Here's my story on fixing the problem.
I noticed that I didn't have any spare Wraths in my collection for casual decks, so I went on Ebay and purchased two Wraths from a seller. They were $1.50 total, plus another $1.50 for shipping. Note to sellers: it is a terrible idea to sell two of a card. People either want one or four copies. Nobody bid on this lot and I stole it.
Unfortunately, there were no pictures with the auction, and when I opened the envelope, I saw this junk:
You're cringing because you've also seen cards that look like this. I had stumbled on the technique to clean up cards when I bought a lot of Tundras from someone and they came, looking like this. I had a spare Tundra and I decided to clean up the worst-looking one with my technique and then resell it. What I bought for $30, I resold for $50, simply because I cleaned it up.
Let's look at how to clean them. I have tried a bunch of different solvents and solutions to get gunk off, and most of them will strip the surface of the card, as well. Magic cards have a water-resistant coating on the front and back, but acetone and alcohol will strip that away quickly. The best cleaner I found for cards is simply a few ounces of very hot water and a drop or two of Dawn dish soap.
Once you have that solution mixed up, dip a cotton swab in it. Then squeeze out most of the water. You are looking for a bare amount, not a soaked ball of cotton here. The reason you don't want to use too much is that it can get in between the layers of the card, which can cause rippling and ruin the edge. You can always moisten a little more, but you cannot remove anything.
Take your moistened swab and gently go along the border of the card, trying to keep on the face of the card and not the side. You will, in all likelihood, not damage your card, but it is worth testing this on a junk Dance of Many or similar card. You will see the gunk lift right off almost immediately. You want the cotton to do the work, not the stick that it's mounted on. If you are scraping with the stick, you are pushing too hard and you will scar the card. Switch out swabs frequently and take your time. It is not hard to do, though, and it gives great results. Check this out:
I have used this technique on Moxes, Ancestral Recall, and all of my dual lands. If you are gentle, you will not damage the cards at all. I am supremely confident in this technique and I think you'll find that your cards look better, trade for more and sell for higher amounts online. I took the second Wrath I got and sold it for far more than the $3 I had invested in the original two, and I only spent ten minutes of my time cleaning them up. What cards do you have that need a facelift? What profits will you unlock with a little care and patience?