In the Pragmatic Programmer book [1], to help make the point that if you keep your code clean, it is more likely to stay that way, the authors cite the "broken windows" theory [2]. They mention a case where police observed an abandoned car lying untouched on a dark street for days, but once a window was smashed, vandals destroyed the car within hours [3]. I don't know much beyond that, but the theory rings true to me and I try to do my bit to stop it, in code and in real life.

[1] https://www.goodreads.com/book/show/4099.The_Pragmatic_Progr...

[2] https://en.wikipedia.org/wiki/Broken_windows_theory

[3] http://www.artima.com/intv/fixit2.html