Honestly, I think Carrey could do a good "serious" Riddler with the right direction. Given the time when BF came out, Carrey was still on fire from his Ace Ventura and Mask films. Having him go all Frank Gorshin seemed to be a no-brainer. Since then, Carrey has shown range in his acting. With a director like Nolan, I think Carrey could pull of a top-notch job. Not saying it should happen, mind you.