Swarmkeeper
Hero
In my view, there are only two ways to treat your dice rolls:
-The outcome is uncertain, and should be determined by a roll of the dice. This is usually how I would treat most attacks and damage rolls in combat, and some ability checks. Once you decide to roll dice, I feel you should also accept their outcome. If you don't like an outcome, don't roll dice to begin with.
-The outcome IS certain, and shouldn't be determined by a roll of the dice. If you decide an action can't fail or can't succeed, then no roll is needed. You already know what the outcome should be. This also means that you probably shouldn't make your players roll for something, if the outcome is predetermined.
I tell my players up front what to expect. If they are considering an action, I tell them if and what they would need to roll for. If it will be an auto success or auto fail, I also tell them up front. If I fear the outcome of the dice, I may even let my players know before they roll, that it is a difficult challenge.
Very much this.
I also am in the habit of telling the player the DC and what will happen on a failed ability check - the fictional justification being that the PCs are bold, competent adventurers who have some sense of the difficulty of what they are attempting and what is at stake should they fail. This also lends credence to the stance that the PCs often have abilities and knowledge within the fiction that the player probably does not IRL - and allows the player to rethink the options and try a different approach if they feel stakes are too high.