His original accent was too efflugent for me 
The absolute worst fake English accent I have ever heard would be the voice of the grandmother in 3-2-1-Penguins! Trouble on Planet Wait-Your-Turn so bad it is embarrassing to listen to - worse even than Dick Van Dyke in Mary Poppins.
I’m not sure if Tim Curry does the worst accents I’ve ever heard because I can never tell what any of them are supposed to be. I’ve never heard him do a sensible American accent though. It sounds terrible.
Of recent memory, Tim Robbins nailed the Southie (ie South Boston) accent in Mystic River quite beauitifully, while Tom Hanks murdered the New England accent in Catch Me If You Can.
“Knawwck Knawwck” indeed.
I’d love sometime to see an actor try to attempt a Pittsburgh accent. Now THAT would be interesting, to say the least.
Oded Fehr in The Mummy.
It’s not just Americans, I can think of a couple really poor Brit attempts at Norn Iron accents: Helen Mirren in Some Mother’s Son and James Frain in Nothing Personal.
Hollywood also gives the same Southern accent to characters from the mansion district of Savannah (MIDNIGHT IN THE GARDEN OF GOOD & EVIL) as they do to characters from trailer parks in Tennessee and Depression era Oklahoma.
A particularly strange case: Lucas Black (Slingblade, Crazy in Alabama) is actually from North Alabama , as was Helen Keller. A few years ago a totally pointless remake of The Miracle Worker was filmed for TV in which Lucas Black was cast as Keller’s teenaged half-brother James. In addition to politically correcting a plot that didn’t need it by giving James a mawkish reconciliation with his father that wasn’t in the original production and detracted from rather than added to the overall value, they *changed Black’s accent * in order to give him a more “aristocratic” Moonlight&Magnolias voice that not only wasn’t true to the character (the Kellers were essentially small town upper-middle class, not high society) but made Black, who used his real voice in his other movies, sound like a 9th grader from Anchorage trying to fake an accent for his class production of MAME. It would have been much much more believable if he’d just gone with his own North Alabama voice.
Someone mentioned Alan Cumming earlier - if you want a laugh, rent Circle of Friends - Minnie Driver, Chris O’Donnell and Saffron Burrows, two British women and an American man (as far as I know) all with diabolical Irish accents.
Mr Cumming, however, was excellent.
And as for Anthony LaPaglia - whoever cast him as a Mancunian in Frasier should be taken out and repeatedley stabbed with a sharp stick.
And while the sharp stick stabber is out there, send him the man who cast Jane Leeves as a Mancunian, too.
First thing I thought of when I saw this thread. The way she flipped back and forth from upper-class Brit to flat mid-west American was dazzling.
Yes, Russian for “Moscow” is something like “Moskva.”
The thing about many speakers of languages that do not natively include a sound like an English “w” (e.g. Russian, German, Polish, Czech) is that they, when speaking English, often get v’s and w’s confused. My German teacher in college would try to say “weak verb” and it invariably came out as “weak werb.” I’ve noticed this phenomenon many times, not that Russians, Germans, Poles, and Czechs have precisely the same pronounciation of their version of what sounds like “v” in English. But for some reason, this particular confusion is common among them.
Possibly this is where Chekhov’s fake Russian-accented English came from: hearing Russian speakers occasionally mix up v’s and w’s when speaking English. I’m not saying Chekhov’s accent is remotely authentic, not at all, but I can see where someone was coming from.
I saw Nicholas Cage in some war movie the other day, and I couldn’t even figure out where the hell he was supposed to be from until I looked up the movie in TV guide. He was Italian if I remember correctly - Captain somethings Mandolin maybe?
Besides, if he had spoke like Guin suggested, he’d have sounded German.