Even though there's a vapor barrier covering the dirt in my crawlspace,
there is still a strong musty smell in there that sometimes migrates into
living area. The soil under the vapor barrier is moist but not wet. Since
the vapor barrier is semi translucent, I can see condensation on the
underside of the vapor barrier at various air pockets around the concrete
footings.

Something could be brewing in those air pockets and is released into the
crawlspace via gaps between the vapor barrier and the wall or around the
posts.

Some contractors suggest installing a french drain in the crawlspace. If I
do that, would it keep the top of the soil dry, or would water still wick up
the soil to the top? In other words, can water wick up from just below where
the french drain is (probably 2 feet deep), and make it to the top of the
soil?