If it's really half-assed, bad work that never met code he'll probably bring
it up, but if you can convince him you inherited it, you're probably ok. If
it's stuff that once met code but no longer does, you're ok. If it's
somewhere inbetween, it's kind of up to the inspector. If it's unrelated to
the job at hand and you explain that you're slowly bringing everything up to
code, you're probably fine.
If, on the other hand, you created the situation due to prior bad work of
your own, then you deserve what you get <g>
P.S. I wouldn't "throw a blanket" like the other post said, that would
arouse lots of suspicion and prove that you were trying to hide something.