Dirty code? That is code produced without considering the maintainability aspect. You can consider a code as dirty when there are tightly coupled, using arrays or map-based instead of data structures, or use hacks like global variables. One characteristic of dirty code, is when the application become large or complex, it is hard to extend or modify and prone to error while doing so. Is you application need the opposite (called clean code)? Not every apps need clean code, and here is why.