Spot On!

This is a slide show of twenty entries. Couple of new additions to the roster of actors with bad accents include: Humphrey Bogart's attempt at an Irish brogue in Dark Victory; Mickey Rooney's yellowface performance in Breakfast at Tiffany's; Demi Moore's awful British accent in Flawless. Bonus -- includes links to YouTube clips.

Toronto Sun, March 2, 2011, "Worst Movie Accents".

WHO: Dick Van Dyke as Bert. MOVIE: “Mary Poppins” (1964). ACCENT SUPPOSED TO BE: British (Cockney). SOUNDS LIKE: A man who needs a new dialect coach.

Dr. Mark Sloan and Mr. Hyde

BroadwayWorld.com, March 1, 2011, "JEKYLL AND HYDE, New Wimbledon Theatre" by Gary Naylor

After Frank Wildhorn and Leslie Bricusse wrought almost as thoroughgoing a transformation on the tale as Doctor Jekyll did to himself, this version provides plenty of setpiece songs, mercifully few special effects and costume changes and yet more opportunities to hear that stage Cockney accent that owes rather more to Dick Van Dyke than to the East End of London..

An Oscar Nod

An English actor who can do a good American accent, chided for reverting to an English accent. Hoo-kay.

The Telegraph, Feb. 28, 2011, "Oscars 2011 highlights: best and worst moments" by Anita Singh

And an honourable mention for Christian Bale, who had an American accent a while back but now appears to be channelling Dick Van Dyke.