I have imported a new feature class into our SDE Geodatabase, sde user is the owner. I have not granted any privileges to roles or users through ArcCatalog and SQL backend shows no permissions to the table, but all of the GIS users can see tha data. I am working with our SQL DBA to figure out what is going on, but thought I would put it out here to hopefully get suggestions on where to look. We are using SQL Server 2012 and ArcGIS desktop 10.2.1. Thanks for any help you can offer!
Best practice is to create one or more users to own spatial data, then load data as that user. Use of the 'sde' user for anything other than geodatabase instance management can result in geodatabase corruption.
The RDBMS software has exclusive management of security in a geodatabase. If you've got all the users mapped to SysAdmin rights on the database server, they will always have permission to access all tables, not matter what has been explicitly granted.