Typically, I'd say co-signing is a very, very bad idea. With that being said, I've done it before and all went well. I only did it because I knew the person well. I've heard the horror stories as well. If you're not prepared to take on someone else's debt or take a serious hit to your credit, DON'T DO IT! Even if the person has every intention of paying you back, they could get sick or lose their job or something similar and you'll be on the hook for that debt.