.
If the lens is that bad, just imagine what the lungs of the previous owner are like!
When I get in a new to me used lens, I smell the packing material that surrounded the lens in the shipping box. If it smells foul, I'll then smell the item that I just purchased. If it too smells foul, and the seller did not disclose the smell in the description, I'll usually request a return rather than mess with cleaning the item up.
In addition to the "rice treatment", on the rare occasion when I did have musty smelling gear, I'd leave the item outside on a few sunny/breezy/hot days. The heat and UV will vaporize any volatiles, which should help mitigate the smell.
I am totally comfortable shooting using either the camera's viewfinder, or the back LCD screen. If all else fails to get rid of the smell, and you are unable to return the lens, you might want to only shoot this lens at arms length from your face using the LCD method of composing.
.