I recently attended an average international conference in Computer Science. This was the first time I actually attended an international conference.
The level of English that I heard during the talks ranged from average to extremely bad (ignoring the native speakers/people that lived a long time in an english speaking country).
I am not a native English speaker, and I do not expect other researchers in the same situation to be as fluent as a native speaker either. But I have worked hard to improve my accent and my elocution to a point where I feel very comfortable speaking the language without stuttering every two words or mispronouncing a lot of things.
As such, I felt extremely frustrated during the entire conference: a speaker with bad English would quickly annoy me, because I felt as if they did not work hard enough on their English elocution, which I believe is an inherent part of being a scientist (especially in Computer Science, where conferences are very common). Therefore, I ended up not being interest in the vast majority of the presentations, even if the subject might have sounded appealing.
How can one improve at looking (or rather, hearing) past the researcher's English, and focusing on their actual contribution?