A gas operated auto (like the 1100) will need to be COMPLETELY broken down and cleaned about every 1000 rounds or so. I have heard different numbers before, but 1000 seems to be the average. That means taking the trigger assembly out, removing the recoil spring, completely cleaning the fouling from the gas ports etc etc.

Now, you should wipe it down well after each time you handle or shoot it. The place that fouls up the most is of course the gas piston area, which is what lies beneath the fore-end. You will see the carbon build up, and it is easily removed.

I have been shooting 1100's for a long time, and have had ZERO problems with them. But, just like a car, you have to perform maintence on it relatively frequently to make sure it keeps running well. If you want a completely maintence free gun, you need to purchase a pump or break action gun. Although, you may well find that without an occasional cleaning, they too will fail.