Jennifer > Status Update

When do you guys decide to DNF a book? I haven't had a problem lately just throwing a book in the giveaway box, but maybe I should give them more of a chance first?

Do you DNF when you no longer are interested in a story? When you look at it and grumble that you have to open it back up? When you put it down for something else and never pick it back up?

Trying to decide if I could DNF my two current reads.