I'm still thinking about dogs...
When I'm working on a new project and thinking very hard I tend to do a lot of drawings that are not at all like what should go in the book... very realistic and detailed, or intensely scrawled, or just plain hairy, sometimes I think about a character for two hours and keep working at the same picture while I'm thinking so in the end it's cross-hatched almost through the paper. Some of them are quite awful, some are rather nice. None of them are ever in perspective.
I've almost learned to not show these drawings to publishers, but sometimes I forget... I always find them interesting myself because they show creative process.
I've had emergency meetings about them sometimes, when publishers call me in and have photocopies of them prepared covered in notes and white-out because they think I've gone dangerously off the rails.
Or people look through my sketchbooks and pick these drawings out and say things like "Wow! This is so much better than what you normally do! Much more mature work!" or they say "This is almost a good drawing, you just need to learn more about line!" (often about the same drawings actually) or "That looks a bit raw art, I don't like it if you do that" - And I go "Arrrgh, they aren't... they're just for me! - Go away!!!!"
But I still find it important not to edit my sketch-books for presentation, I think that would lead to me throwing things at the wall.
I've noticed that a lot of professional illustrators I've met have sketchbooks completely devoid of such things, instead just sketches that any publisher would accept as roughs that aren't inked in yet, or interesting yet non-threatening exercises in style. Maybe it's because I don't think in pictures.
Anyway, more dog-thinking now.