Off Topic. long post is long
Pfft.
Watch "Lemon Angel Project" and tell me if you think that is 'Good acting'. Seriously if you can't hear it then I envy you. And it's not hard to pick out bad acting and bad singing in another language.
If it was however -something like Theater acting, I would agree with your statement.
My examples.
-myco who played Mitsuki Koyama in the "Full Moon wo Sagashite" (in my opinion) was terrible, her acting was stiff and the voice choice didn't fit the character at all, I was literally laughing every time she spoke - She did alright as the show went on - which usually happens with a lot of VAs in Anime. The lady is great at singing but Voice Acting isn't her thing.
-Another Singer who voice acts is Momoi Haruko - who I love and a big fan of her singing, but when it comes to voicing characters it's a mix-bag. Sometimes she shines as the character, other times you can just hear the stiff acting but also hear the enthusiasm. She's popular so she is used a lot.
-Then there is Saeko Chiba, perhaps it was just her Dokuro-chan role that made me wary of her acting, I'll check out more of her work. It sounded like she had this "OooooH ... REeAL-LY!?" type of way of acting, like fake. "NAaah-Nii?!". I think it was just this role that bugged me, the show itself is amusing.
There are Anime roles when the voice actor is just terrible, yet when they do a different Anime role they are terrific. Perhaps the role was just wrong for them or the director wasn't...directing lol
With "Air Gear" Kenta Kamakari as Ikki was just terrible I was literally cringing, the guy is a good Stage-actor, but as Ikki his acting didn't improve till the show was nearing it's end. I felt that half the Japanese cast for Air Gear was just bland. Chris Patton as Ikki and the English cast (to me) was a lot better.
With exceptions when it came to Akito/Agito. And I mean this for both dubs (Jnp and Eng) I found both voice choices to be unfitting, but the VAs were good at bringing out the character, and their acting was enjoyable.
I watched "Disney's Hercules" in Japanese and was surprised at how bad it was. Not because I am use to listening to English (I watched it in Spanish too) it was seriously just badly done.
Most people who say that the English dub track is bad, is mostly just ranting and look at Japan as some shinyland of happy. You can find clips and episodes of anime in Spanish, French, German, and people will say the same thing because they just have a preference for listening to Japanese, even if the acting is bad. And when it comes to popular Anime you definitely see people making claims about how "Inferior" every dub is.
On Topic.
I think you should actually ask an English dubbing Anime voice actor about this. Many of them have blogs and emails they reply to. The only replies that can be gotten here is *points above* Opinions. And how much time is put into the dubbing. And what we think happens.
....? Unless that is what the purpose of the topic is.
Since Anime is an industry in Japan, of course the way of getting voice actors is different from other countries and each country has their own method for their own Animation industry.
In Japan there are schools for voice acting and lot of them are in music groups. It's literally a career choice and the people are practically celebrities as-in movie star status.
Those are the only two major differences -from my view. Overall, many voice actors have various careers, it could be Stage acting and Radio that gets them chosen for a role.
A thing they have in common is that they [Voice Actors] love their work. They have opinions about the characters they play and they have their favorites. A lot of people think you have to like everything about the character to play the part - well from an Otaku perspective.
And then there are some Studios and VA's go out of their way to please Fans.