Tends to be a more laid back crowd (hobbyists, students, housewives, etc). You see familiar faces each sale. You can almost tell by looking at people and their behaviors what types of books and interests they have. A young woman with a little girl was at one of the recent ones I've been to. Her little daughter said, 'Can we go now?" While rummaging through more cook books the mom replied, 'Oh, not yet. You know how mummy loves pies!" .
That's awesome I love book sales, you can get really good ones for cheap if they're slightly torn... I got a bunch from Indigo in the summer: history of science, mirrormask, a book on cults, and a few little ones that are dedicated to different artists (Van Gogh, da Vinci, etc.) Haven't read any of them yet with school, but I'll get to it when I'm old and grey They're good to have too, when the apocalypse comes and we need stuff to burn for warmth.
I've never been to a book sale, but the library in town gives away books they don't want anymore. They just stack them on a cart in the foyer and you just take what you want. I got 5 books by one of my favorite authors the other day. They all suck ass because they are actually by ghost writers who aren't all that great, but hell, I got 5 free books.
Yes. Various groups do them- libraries, community colleges, universities, community groups, etc. They often sell other media such as CDs, DVD, old VHS stuff. Sometimes there are bake sales or hot dog roasts to go along with the event. The events help raise money for the community. Sometimes you can get early picks of the books if you volunteer to help set things up. .
When the apocalypse inevitably comes I will be using books to wipe my bum, as I will be shitting myself quite frequently. As for book sales, I tend to like buying books from car-boot sales. It's not very cool, but it serves me well.
I have started buying my books from charity shops. We have good ones around here, and I always find ones that I have been meaning to buy. When I was little each year our library would have a book sale and I loved it, I'd always come away with bags full of books.