Bad code is a virus

You did not document your system. You were in a rush and hacked the implementation. It happens even in the best families. Then someone else comes, and has to use that system. He does not find any documentation, so he searches in the code. It finds how you used it, copies and pastes. Code is documentation. Bad code spreads.
Always comment bad code (hacks etc). Always. Remove it at the end of the project. If you're the user, always ask if you don't find the documentation. Do not ever copy and paste code you don't understand/you're not sure of, do not trust code.
We can win, with your help, bad code can be eradicated.