The Worst Accents in Screen History
No, Meryl Streep's name is nowhere near this list.
But if you click on this survey, you'll find no fewer than two Brad Pitt performances (one of his accents is described as sounding merely like a sore throat), a legendarily bad Cockney accent by Dick Van Dyke in Mary Poppins (" 'Allo, Guvnah!"), plus a Leonardo DiCaprio turn that actually nabbed an Oscar nomination. (It was for Blood Diamond, in which Leo was supposed to be from Zimbabwe but sounded alternately Australian and South African.)
Keep scrolling down for the special mentions, like John Wayne as Genghis Khan--possibly the most woebegone bit of casting in cinema history, except for Wayne as a Roman centurion in charge of the crucifixion in The Greatest Story Ever Told. I could never figure what that accent was doing in the bible!