Difficult to reconcile

I'm having a bit of a philosophical crisis. I've been listening to someone present an argument over the past few months. Some of what he says makes sense to me; some, not so much. But this is not a big problem of itself. Today, I realised why the argument as a whole makes me uncomfortable. The fundamental basis of his argument is so deeply impoverished and flawed, that it colours the rest of it - even the bits that seem to make some sense. So where does this leave me? Not all of his message is complete horse, but how much credence can I give to it when the foundation is so shaky?