Hacking into networks can be fun when it's taking place in your personal lab. At some point, however, you might need to take it to a real environment. When that time comes, it is critical that you make sure you conclude things properly. For people providing penetration testing as a service, you must show evidence to justify your findings or you won't demonstrate enough value for future business. This means documenting everything and not leaving behind possible problems caused by your services. For attackers, you will want to remove your footprint so that the authorities can't track you back through a forensic investigation.

When it comes to reporting identified network weaknesses as a paid service, people don't like when their child is called ugly, and will probably challenge your findings. It is important to document the entire process so that it is repeatable, assuming that the network is in the same state as when the penetration test was performed...