All I can offer her is anecdotal evidence heard from retired officers but they made it sound like this is a problem in every department. Maybe not to the same degree everywhere, but in general bad things happen to people who follow the rules when the rules implicate wrongdoing on the part of another officer. Weather that's shunning, teasing, pranks, being assigned to only specific duties or shifts, or worse is gonna depend on the situation. The impression I got was this was commonplace and most officers understand the unwritten rule to not report thing little things (and sometimes even the big things) that could get a fellow officer in trouble. It works too because at the end of the day you gotta entrust your life to the people you ratted on, people who know how to make things look like accidents and have a network of people that will vouch for them.