Carbon has nothing to do with rust. Rust is one of several forms of iron oxide. Carbon steels are steels where carbon is the major alloying element for the iron. Tool steels and stainless steels have other elements, like vanadium, molybdenum, nickel, cobalt, chromium and the list goes on. Stainless steels are steels that have at least 11% chromium. Different alloys have other things in it as well. Carbon steels rust so easy because the oxide that forms flakes off because of its larger volume, where the stainless steels will be harder to rust because the oxide that forms on the chromium doesn't flake off, much like aluminum's oxides.
Stainless can be passivated to remove as much reactable iron from the surface as possible, the same way a properly a blued gun will react as much surface iron as possible, preventing rust. If a buffing wheel thats been used with carbon steel, or a plain steel wire wheel, is used to buff a stainless part, some of that iron can be deposited on top of the stainless, and cause problems with rust, even disrupting the surface of the stainless because of the rust's intrusion into the stainless' grain structure.
Scott