This is not garbage disposal. Among my criteria are that the books concerned must be speculative fiction of some kind - what earthly use would the con have for a historical romance or a thriller? (Unless, of course, the author also writes SF) They can't be books the author has personalised to me because it would be just my luck if the authors saw them. They must be in perfect condition (though I did slip in one or two books with a single crease in the spine because they were part of a trilogy.) They must be a book that I either read once and knew I wouldn't read again, because so many books, so little time, or that I bought and just didn't get around to reading, but hey, if I do want them there's the ebook. I put back one book I had read and loved, but only once, because the ebook had an 11 megabyte download. I may want to read it again some time. Pity, because it was a trade paperback. If they're YA fiction, my own library has first dibs, although in one case, the Hunger Games trilogy(which I do have in ebook now), I am giving it to Continuum because I have a full set at school and no space for another. That set is perfect condition - I read the lot in three days, no time to crease the spines! I'm also giving them my Harry Turtledove YA Crosstime Traffic books, a wonderful series, but I've only read the books once each and I suspect my students won't read them.
I'm arranging for a kind gent from the committee to pick up some boxes next week and am determined that the bare minimum of books will be a hundred. I can't do it again, at least not this year, so the more now the better.
A the same time, I'm unearthing books I had forgotten I had, such as the DAW collection of SF published for its 30th anniversary - that one is getting one chance from me and I've slipped it into my tote bag. I can always enjoy short fiction, you can read it on the tram and finish before you reach your stop - and it fell open at a Robert Sheckley story! If I've done with it by next week and can bear to part with it, into the box it goes. If I just love it too much, well, I have a few spaces now...
Reluctantly I put into the donation box an Anne McCaffrey book I bought at the now-defunct Of Science And Swords bookshop but never got around to reading. If I decide I do want to read it, iBooks will be likely to have it.
They can have Abraham Lincoln Vampire Hunter which I found entertaining, but was sorry I hadn't been able to just borrow from the local library and return. It's in perfect condition, read once. Likewise the one about the "demon hunting soccer mom". Read once, never again.
There were a couple of Arthurian novels I hadn't enjoyed but someone else might, and quite a few I gave decent reviews at the time but won't be reading again.
I also found my copy of Dining Out On Babylon 5, long missing, which I won't be giving away! It's a delightful recipe book which features introductions to the recipes by various characters from the show - the one by Londo Mollari was a hoot! That anecdote about the emperor who took the encouragement to joy through food rather too seriously and crushed a wife or two had me rolling on the floor laughing. I must reread and post a review, however late in the piece it is.
Off to the city to find sandals and then back to the book sorting, which is a pleasure in itself.