When do books become clutter?

When do books become clutter?
Originally uploaded by Jaydot

This question came up in the Unclutter Group on Flickr.
I suppose it's when you finally realise that you're not going to read them, or even open them, ever again and that all they're doing (well, a lot of them anyway) is cluttering up your life.
I seem to have reached that stage...
Of course there are a lot of books I could never part with: because I reread them, or look things up in them, or because I've had them for over fifty years (and still read them occasionally for old times sake).
Those books will stay and be cherished.
And of course I buy books - although you can find almost anything online, I regularly run into books I cannot live without.
But the others have got to go.
First problem I run into is that I have practically all my books entered in Library Thing. So if I let them go, I'll either have to remove them from LT, or retag them.
Next problem is what to do with them. Bookmooching, much as I love the concept, is too time consuming. Selling them... well, perhaps a few might be worth putting up in the second hand section of Bol.com (the Dutch Amazon). But overall giving them away seems the best option. The church in my village organises a great sale every spring, perhaps they will be happy to have them.
So in the coming weeks, I'll be pulling ten or so books off the shelves every other day, tagging them "decluttered" in LT, and putting them in a box for the church people to collect.
The books in the photo are the first ten with the new LT tag.
It's a horrible job, but someone's got to do it.