When I went to a family counseling program, they had a list of 10 to 15 questions on the wall to help a person gauge whether or not they have a problem with addiction. I remember the person I was there would have answered 'Yes' to darn near all of them. It was obvious he/she had a problem. I don't know if that's a standard list or one that this facility made on their own.

A common theme seems to be that a person needs the thing they are addicted to function at a basic, normal, or even high level. They get anxious when they don't have it. They will lie or make excuses to get it. They will make several attempts to quit yet come back for a number of reasons they rationalize. They have problems with their family, friends, or job as a direct or indirect result of the addiction. There are other warning signs, but those are the ones that stick out.

At any rate, if you ever want to delve deeper into it, there are many resources available. There are several AA meetings that you can go to as an observer - just make sure it's one where anyone can go as opposed to one where you must be an alcoholic to go.