I've used swaptree successfully several times, but have stopped until they change their policies about "all books/cds/etc are the same." I don't think it's fair to send my unopened book to someone and get some beat up thing in return.
Sometimes all I want is to read a book once and give it away when I'm done. In that case, any condition book is fine. Sometimes, though, I want a specific book because I'm collecting that author's works. In that case, I want a book in as 'near new' condition as I can get -- and will happily trade a 'near new' book of my own. The way it works now, swaptree won't let you do that.
Those of you who have used swaptree [or other swap services] before: what are your thoughts on this?