Worth a trial: Domains for free instead of selling?

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As I know for a fact it's so much easier to take a 10 year old site and build up SE traffic than buying a new domain and starting from scratch. However, I find it difficult to find buyers for aged domains that appreciate this value. Well, maybe they do, but in most cases they either believe I am desperate for 10 bucks or short of funds to extend registration. Of course that's not the case. I am just giving up on some niches like smother, lesbian, bukkake, cumshots.

My idea: I will give away some domains for free in exchange for backlinks. Now, my question is: how can I make sure buyers will keep up links after I push domains over to them?