Playing dumb is a great technique to get you closer to the footage that you want...
but, perhaps, you know you shouldn't be getting.
Let people think you're dumber than you really are.
Don't show all the cards of your intelligence - at least, not yet.
The point of this is to get in the habit of crossing lines of discomfort to get awesome footage.
If you get called out on it - just play dumb.
You're not at fault for not knowing what you don't know.
But, of course, you do know.
Because you're getting the good stuff.
This brings me to my next point...