A lot of people I have seen have an inability to properly make their dogs understand when something is bad. If a dog has done something wrong and you've found out about it after a while, there is absolutely no good in disciplining them at that time since their brain is such that they don't understand what they did wrong.
For example, if you come home and find that your dog has chewed up all the papers in the house, and you yell at him, he will not understand why you are angry. Only that you are angry.
In order to effectively make your dog change their behavior, you need to catch them in the act. Either that, or just as they are about to make their move so that it's crystal clear what is happening.