I have a good wooden salad bowl that becomes rancid, try scrubbing with soap and water, and even soak in water and bleach. The odor still exists.
Following is the answers given by the company that made the wooden bowl:
We recommend using a non-abrasive scrub pad, lemon juice and pumice powder to scrub the accumulated oil over the years. In the past, the use of vegetable oils such as corn oil, olive oil, and even lard had established a culture for bacteria and became viscous and thick, and contained multiple layers of oil.
If you scrub the bowl with pumice and lemon juice, you will safely remove the oil layer. After washing the cleaner and be sure to place the bowl on the wood, apply a layer of mineral oil to the bowl and allow it to soak in the wood.