The context you are asking about does not necessarily invoke deception.
I also work in UX.
When testing user interfaces you need to ensure you don't inadvertently force your test candidate to use the interface in a certain way simply because of the way you ask questions.
If, for example, you want to discover if your users can find the button that starts a particular function then you would avoid asking them to 'click the button in the top corner of the screen'. To avoid 'leading them on' you might instead ask 'How could you start function A?'. This means that the only thing you have put in their mind is 'Function A' and how to start it rather than setting them looking for a button in a particular part of the screen.