Not to be rude, but the worst person to critique a foreign accent is perhaps the foreigner trying to fake it!

You're not being rude but dboreham is correct. Wyoming accents are not strong compared to most states in the US.

English people are terrible at weak and standard American accents; they sound like they're head-injured, and put 'r's at the end of works that end with 'a's. The funniest examples are French & Saunders' bad American accents (but at least they're aware that they're terrible at it.)

English people vastly prefer trying to do a sterotypical New Yawk accent because they can hide their mistakes in the extremity.

Afaict, Scots are the best at doing an American accent, followed by the Irish, followed by the Australians and the Welsh, then you get to English people.

I know a number of people who moved from across the pond that actually do American phonemes fairly well. What gives them away are minor inflections and sentence cadences that sound a little off. Hard to describe, but it makes them sound like the are trying to speak to everything “as a matter of fact” and towards the very from of their mouth. For an example, listen to Freddie Highmore in season 1 of Bates Motel.

I don’t buy that. I also find it funny the one example you use are comedians (not actors) who are probably doing something very stereotypical.

Dominic West and Idris Elba are both English and often cited as 2 examples of British actors everyone thought were American due to the wire.

There’s an interview with snoop dogg where he was allowed on the set of the wire and couldn’t believe idris was British when he introduced himself.

Damien Lewis is also English and often cited as a master of American accents.