I just purchased a Dracena corn plant. At home I noticed that the canes were coated with a green substance and the plant was emitting a moldy (musty) odor, which is now permeating throughout the house. I washed it down with a soapy water mix and was able to remove most of the green substance. However, the odor persists.
Odor Emanating From Newly Purchased Dracena Corn Plant
Certified GKH Gardening Expert
It sounds like the plant has root rot and what you smell is the roots decomposing. There is not much that can be done to help the plant, but this article may help:
If it smelled like that when you bought it, I would return it to the store. They over watered it and this is what caused the root rot.