I rate them like your friend. I don't go by a book's rating on goodreads to determine if I want to read it / will like it or not.

I only use the rating to remind MYSELF what I liked or didn't like - and I suspect quite a large number of other goodreads users do the same.

Personally I don't give a 1 ever because that would be a DNF - and you're right, if it's that bad, then it's probably on me selecting a book that's not my taste. Those I simply shelve as DNF, don't rate and move on.