Really depends. If you can run the profiler for extended periods, you can still easily miss something which is only used once a year.

I tend to rely on inspection and logging because I like to design systems where the database exposes as much as possible in a controlled fashion (i.e. mainly stored procs). It is relatively easy to find and instrument any stored procs which refer to a table to find out when they are used, and you are assured that you catch all usages. You can simply use the SQL Server dependencies information (make sure it's refreshed) to inventory the system.

In a system with direct table access, it's not nearly as easy.