Rusty inside Zenith carb

[Clem Clement]

I loaned a Zenith to a bud two months ago. He did not run the car much but left the carb full of gas. Today we removed the carb and put his original back on. My carb has a goodly layer of rust in the bowl. His gas is old. Do I guess it is the alcohol in this bad gas absorbing water and rusting the carb? Rust is loose to the finger touch. (I had rebuilt his carb and when we installed it, the car fired right up and ran on the stale gas but what a nastly exhaust smell.)
clem