Justify NOT using (nolock) hint in every query

Have you ever had to justify NOT using a query hint? I am seeing WITH (NOLOCK) in every single query that hits a very busy server. It is to the point that the developers think it should just be on by default because they hate seeing it in their code thousands of times. I tried to explain that it is allowing dirty reads and they will end up with bad data eventually, but they believe the performance tradeoff is well worth it. (Their database is a mess; no wonder they have performance issues.) If you have a clear example of how to present the case against this abuse of the NOLOCK hint, that would be appreciated.