My basic rule for data is, unless there is a life and death scenario unfolding, bad or unclean data is not going to be used. I have yet to encounter a situation where releasing data, which will eventually wreak havoc throughout the school, is an essential and lifesaving endeavor. Delaying systems access due to data issues is difficult. Even the smallest of systems have vocal advocates who will passionately state the damage being done to learning for every day a system is offline.
The best way to exist in a data-driven environment is to be prepared. Being prepared means being aware. Awareness comes from a regular, I would argue monthly, check of all core databases and having policies and procedures for correcting problems.
The real question is this: how does someone not involved in direct data management, check data? And how does someone who is an end user of data set policies to protect the data they need?