I recently binned a book that I picked up at a book swap. The blurb sounded like one of those fun 'witchy / paranormal' novels that are popular at the moment.
As I began to read it, I realised that it was quite sinister, as if the writer seriously believed some quite unpleasant stuff about witchcraft - I then noticed that it was privately published.
I put it on a shelf - as others have said, throwing it away seemed like a 'sin' but I did feel bothered by it being picked up by someone impressionable. I debated if I owed the same consideration to a 'privately published' book, and if policing the reading habits of others was appropriate anyway!
A neighbour and I were having the same conversation - and she is someone whose judgement I value, so I mentioned this book. She said 'oh, I have met that person, she is very strange and I think you're right to throw the book away'. When I remarked on the co-incidence of her knowing the author, she said 'not really, she lives locally, publishes privately and puts her books into swops and charity shops to get an audience'. After that I felt no qualms about binning it!