I understand the frustration, but most fansubbers are outraged at the mention that their volunteer work isn't the quality you're looking for. The arguement is: they're making available to watch anime that isn't otherwise available (yet). There are 2 things you could do if you're looking for, say, a textless OP to screencap from
1.Be the fansubber's friend and ask for the raw, but TV rips aren't great quality and
you'll probably re-cg the image anyway
2.Buy the disc (either domestic, if it's released, or import, HK may be acceptable quality)
and capture without subtitles on.
As for over-translation, I think some groups enjoy it, and maybe they're considering that viewers in certain countries might not understand the situation from the visuals.