today I've discovered a very interesting setting in Global Settings section in Nintex Workflow Central Administration and I want to share it with you .
and "Workflow Task View" is the default value, that you change if you want..
This is the name of the view that specify which properties are shown in a default task form, if you don't have a view named like that, then all the properties will be shown (it's the most common scenario I've seen).
If you create or edit such view, you can choose what you want to show or hide in task, so that user doesn't see all the "hidden" fields you can have in your list/library that are useful for the workflow but not for him/her..
Unfortunately this settings is global for all the farm and if you want to have different view for different tasks that run on the same list/library, you can't .. if you think this could be an interesting feature, I've also created a request on uservoice: Move Task form properties view setting to the task level – Customer Feedback for Nintex