These studies are interesting but I think it's disingenuous and counterproductive for the left to blame Chow's failed campaign on such prejudices. While I'm sure they exist, there were far more fundamental problems with her campaign which had nothing to do with her communication style, as recently summed up by John Lorinic
here.
That being said, the problem I find with her communication style has nothing to do with the quality of her English and everything to do with her speaking style. You'll notice that right before she makes the most substantive or poignant point, midway through her sentence, she pauses then slows down and softens her speech, as though she were speaking to a child, so as to emphasize the point. First off it awkwardly disrupts the pace and flow of her sentence, but more importantly it comes off as condescending, particularly when she's addressing someone directly. I could absolutely see how it rubs people the wrong way.