I've always used acidic marinades and I don't care whether you have SS, Enameled or Cast Iron you're going to eat up the flavorizer bars, grates, etc. on a WSM, EX, Gasser or Charcoal Que. My EX4 doesn't look quite as rusty as abmet's yet, but I did notice that before I got a cover for the EX, the first light rain we had I wound up with a grease pan full of water and a fair amount of rust on the fire pot shield. Water was able to enter through the top of the hinge I guess, but keeping covered fixes all that. I do try to clean the inside of the smoker every few uses but usually a light scrape, and de-ashing followed by a paper towel wipe down of the flavorizer bars, heat deflector and the lower half of the smoker and we're good to go. I'd like to think a nice build up of grease would help prevent the rust but there's probably a fine line between a nicely seasoned box and a high temp sear turning into a grease fire. I think as long as you wipe things down you're still keeping a somewhat greasy surface behind (at least greasy to touch) but i think we can all agree, some of the hardware will eventually need to be replaced.