IMO you're a client consuming the data. Therefore it needs to be set up in a way that you can access it for your tools.

This may mean datamarts, cubes, denormalized tables, views, or anything else that meets YOUR business requirement. A separate database for reporting makes it much less painful in some respects because you're not accessing the clean happy data. 🙂

You should also feel comfortable going to a database developer and/or DBA for help with performance tuning queries if you're not sure you're doing it in the most efficient manner.