"Under the broken windows theory, an ordered and clean environment, one that is maintained, sends the signal that the area is monitored and that criminal behavior is not tolerated. Conversely, a disordered environment, one that is not maintained (broken windows, graffiti, excessive litter), sends the signal that the area is not monitored and that criminal behavior has little risk of detection."
Improving and more importantly maintaining the environments where people live does reduce crime. Most of the problems people have with broken windows theory is how it has been used to justify excessive policing that victimized people instead of improving things for them.
https://en.wikipedia.org/wiki/Broken_windows_theory
It is 'just' a criminology theory, with many people who disagree with it.