This sentence doesn't make sense in English
I agree. A better translation would be “I like dresses; well, not all of them”.
Or - "I don't like the dresses; at least, not all of them."
Yeah the thing which gives the sentence meaning is the punctuation. it should be a semicolon and not a comma.
Yeah... it should be more like "at least, some of them"
Why is it 'les robes" and not "des robes?"
If you're referring to dresses in general, you use the definite article. I agree with others, however, that this is a pretty weird sentence in English.
it would make more sense with "at least" to say: "most of them" not "not all of them." So the better translation would be: "I like dresses, at least, most of them." OR you could say: "I like dresses, but actually, not all of them."