There's no mistaking a happy dog. The wagging tail, the eager eyes, the smile that's impossible to fake. A happy dog radiates pure joy. Yet the mystery remains: What's really going on behind those waggish grins? Are our dogs laughing with us? At us? Are they operating at a higher stage of enlightenment . . . or just buttering us up before we discover the tiny, torn remnants of burrito wrapper suspiciously dotting the hallway? In Waggish, the infinite...