Paddock Hill on Brands Hatch is definitely evil, not just because it's really tricky, but because if you're the slightest bit late on the brakes then you know you're screwed right away, but there's nothing you can do at that point to save it, so you're just along for the ride for what seems like forever before you finally go flying off into the sand.
Edit: Similarly, the first corner on R246 is terrifying in a fast car, because you hit the brakes and then have ages to wonder if you got it right or not as that wall keeps rushing towards you...