What's that? You rolled a natural 100 on that (meaningless) observation check I just had you roll? You notice the produce stall has ants and track the line of them back to a crack in the wall. Do you tell the merchant?
I've done that too! I've had players want to contribute to the point that it was interrupting game-flow, so I gave her the most detailed information she could have about the tree in the Elven forest. Then when it came time for combat, she fumbled a couple of times and I told her she shouldn't have wasted all of her good rolls.
It's the law of averages.
I do have players give me a dice roll for no reason, it keeps them on their toes and invested n the scene. Whenever possible, I let them roll their own fate. It lets them see that I'm on the up and up and not just manipulating rolls behind the screen for my own ends and I like to let them be the victim of their own dice.