It was a misunderstanding on her part, not a deliberate 'deception' on his (part). [=he didn't try to deceive her or lie to her]
The article describes the government's use of 'deception' [='deceit'] to gain public support for the program.
She 'practiced deception' on her unsuspecting clients. [=she deceived them]
(..) ...and I know what you're not. I'm the best friend you have and I'm gonna help you understand something. You're no fucking cop. He's right. We deal in deception here. What we do not deal with is self-deception. Five years from now you could be anything else in the world. But you will not be (..)2006 The Departed