Ranking bad content with white hat techniques

ranking good and interesting content its not too tough, you just got to know the ABCs of linkbuilding and show a bit of initiative and consistent work, but how do you rank content that isnt particularly interesting, or in some cases, its downright useless? and on top of that, do it with white hat SEO?

any specific techniques or ideas that you could share?

I work with a client that has no writing skills whatsoever, doesnt want to hire any writers, and her articles are snooze inducing. Her topic of "expertize" is so far away from my knowedlge that I couldnt add anything of note either, she keeps sending me basically rubbish while expecting to get ranked for some competitive terms. I have a dozen clients like her, that never produce quality content, and yet demand to have high rankings, but most of what I read about SEO focuses on creating great quality first,

what if you dont have any decent content to begin with , and you can't "fix" it? how do you rank crap content using only white hat SEO?