people who dog-ear should be punched.it's disrespectful.
Punching people is kinda disrespectful too. I don't use bookmarks unless I'm on a plane and have my ticket handy. I pretty much just open the book to about where I think I left off and start reading. This means I'm not as efficient about reading, but it allows me to savour the book a bit longer.
The Kindle has robbed me of this joy and finds where I left off with ruthless precision.