1. Don't trust SeatGuru.

2. Airplanes fly at an incline of about 2-3 degrees. If you were fully flat your head would be below your feet, so many people actually put the head back up a few degrees. Add to that the flimsy airplane pillows which are much less substantial than the ones most people have at home, and you'd not want a fully flat bed. In fact, I always choose rear-facing seats when I can.