Hmm... It's a toughie. And a boat I've been in before, ha...
Usually I wind up holding onto an item for a long time if I'm gifted it but can't use it. I feel super bad thinking about selling it, because I think, someone gave me the item out of the kindness of their heart.
Sometimes, I wind up finding a use for the item. Sometimes I don't. If it was an expensive item, I have a hard time selling it, but sometimes I will to help get a different item. After sitting and staring at my computer screen forever and a year debating if I should or not. xD;;
Though on the flip side. I don't care if the person sells an item I give them. I suppose I can thank having a brother in real life who never keeps any gift given him for more than a few months for that. xD I usually try to find something on a person's whishlist, but if I can't find something within my price range and still really want to send them a gift, I'll try to find something I think they might like. If they don't, though, or even if they do and just get tired of the item, I don't really feel hurt if they decide to sell it.
Likewise, I don't stalk them to see if they use it or sell it, either. It's theirs, I gave it to them, they're free to do as they please with it.