My problem with (some, not all) dubs usually stems from two things:
1) The English VAs often don't put nearly as much emotion into their voices as the Japanese ones. This may be my personal penchant for melodrama coming to the fore, but usually it seems like the Japanese VAs will take things to a higher level than the English ones. Whether this is the fault of the actors themselves or the directors or what I dunno, I don't really know that much about the process, but it bugs me.
2) If I've already experienced the Japanese voices, it'll often bug me if the English dialogue doesn't follow the same pacing and inflection. This is probably more my problem than their problem, and could very well be a "they changed it now it sucks" effect, but it still bothers me. I know it's impossible to get exactly the same due to the differences between spoken Japanese and spoken English, but still. Bugs me.
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