I haven't found a way to do this, but maybe I missed it somewhere. I'd like to be able to search for people that want a specific card that I currently own, and that's it. I see you can do that currently, but you have to specify the card you are looking for in return or that card needs to be in your wishlist. In my situation, I just know that I would like to trade some cards away (I have playsets or more of cards and I only play EDH anymore), but I don't have any specific cards in mind that I'd like in return. I'd love to see who has CardA on their wishlist, and then browse their tradelist to see if anything interests me.

Thoughts?

You don't have to specify a card that you want.

Select Trading opportunities > Change the setting for "I'm willing to trade" to "Specific cards" > Enter a card you have on your tradelist > Click Apply Filters > Profit.

The dropdown when entering the card name doesn't automatically display specific copies of cards from your tradelist so you have to enter that criteria manually. Generally though it's better to leave the card attributes blank as that will provide you with the most hits.

Edit: Forgot to mention that if someone wants a specific version of a card that doesn't match the copy(copies) you have available they will show up on the trade opportunities list, but you won't see that card listed under the list of cards they want from you.