One problem with databases.
Is often user's have a very poor understanding of set theory, and eventually will believe that "SELECT * FROM GuiltyUntilProvenInnocent" is an accurate and acceptable subsitute for actual investigation and evidence - why bother looking for suspects not in the database when you can just expand your WHERE clause till you get a shifty looking supsect match.
There is a prevailing "CSI on telly" attitude that you can get a 100% accurate database record in seconds, including their name, picture and what they had for breakfast, in seconds from a magical system, the GUI of which would actually display the records its searching in real time for your users delectation!!! In reality I am sure the databases are not that clean, the algorithms to match are not that infaliable, the GUI's not that ridiculous and the operatives not that smart (or attractive).