Speaking from my relatively limited experience at the PTO, I'd say that they do have a pretty large body of fluent English speakers in the examiner corps, many of whom are first or 2nd generation immigrants. That being said, they have a surprisingly large body of people that just plain do not speak English. We're not talking about "your accent is difficult to understand over the phone" so much as "it is impossible to have even a semi-confusing conversation with you because you don't know enough basic vocabulary to complete an ordinary sentence without choking"
I ended up drawing pictures and using keywords to explain what i was talking about but mostly I did my best to avoid those people in favor of intermediaries. God forbid you are stuck with them as an examiner for your application.
Granted, English isn't my first or even second language, but I still like to make fun of the Examiner Corps. I don't consider mild or moderate accent to be a problem, but some folks over there sound and write like they've just enrolled in the Aprenda inglés section of the local community college. Consider this - to get a job in the PTO you must be a US citizen. To become a US citizen, you must hold a green card for at least 5 years. Given that it takes many years to obtain a green card, it would be fair to assume that most foreign-born Examiners start at the PTO after they've lived in the US for at least 10 years, probably a lot more than that. And yet, some of them speak and write as if they just came off the boat.
Seems to me that the PTO should simply enforce a fairly high language fluency standard when hiring. We are really in the business of "wordsmithing," so why should the fate of our patent applications depend on those who often can't seem to grasp all the intricacies of the English language? The presence of such folks in the PTO (albeit often exaggerated outside the PTO) still reflects poorly on the Corps.
I don't disagree with the assessment that there're examiners with English difficulties at the USPTO. My comment was directed to the generalizations and exaggerations in this anonymous, public forum, in particular the ridiculous statement that equates people not having English as their first language to unfluent English speakers on the phone. And tech_spec proved my point, if his spoken English is as good as his written English.

1.) Because overall they don't complain as much as American's do (at least not in our language

).
2.) They have a much better work ethic (on average).
3.) Some of them have relatives in their home country that they support and send money to so they take the job more seriously.
4.) 98% of the day you don't need to speak english.
There is a reason why the majority of SPE's and primarys are foreigners (many who I cannot hold an understandable conversation with). Most Americans quit after a few years because it is more stressful than regular engineering jobs. Don't get me wrong, I would love a fluent english speaking corps for the sake of the attorneys. However there would either have to be a hefty increase in salaries or a doubling in production...because I don't see them replacing a few thousand poorly spoken foreigners with American engineering graduates anytime soon.
See how many such mis-statements you can find in the above? Here's one:
... a few thousand poorly spoken foreigners with American engineering graduates anytime soon.
"a few thousand"? Out of some 6000+ examiners? No wonder the USPTO is in such a crisis!
And what's a "foreigner"? Don't you have to be an American to work at the USPTO? About a month ago the press was claiming "Americans" having won certain Nobel prizes despite those "Americans" having been born in Australia or China. Is the governor of Calif. a foreigner? How about the USPTO Director Kappos? And the Secretary of Commerce, Kappos's boss? Both have parents or grandparent who were immigrants.
There're several stereotyping opinions in the above that're not worth to time to respond, especially "count Monday" is coming.