Could you confirm that the terrible translation you are referring to is the one by the aptly named, if nothing else, Peter Collier? I assume that it is, but you can never be sure on Amazon, as often reviews for slightly different products get lumped together.
This translation was my first exposure to Zola, and you'll be happy to hear that far from putting me off, I am eager to read more. I am disappointed to learn that this is a rubbish version; my efforts could have been spent reading something even better. I must say that some of it did sound a bit clunky; certain phrases were used over and over again, which sounded especially strange in the mouths of different characters. I imagine it was a technique in the original French that didn't translate effectively.
I would like to read the prequels, L'Assommoir and Nana - do you have any recommendations for good translations? I suppose the best thing would be to get hold of a French copy.