Blue
Ravenous Bugblatter Beast of Traal
I honestly couldn't make much sense of the scenario, so I'll defer to [MENTION=16814]Ovinomancer[/MENTION] on the response as it sounds appropriate to what I could take away from your example.
Also, it would be great if you'd stop accusing me of sidestepping or trolling or any of the other things you've rather rudely accused me of in this thread. It makes me want to stop responding to you at all. I've answered your questions to the best of my ability, or others with whom I agree have done so, and have not at any time attempted to troll you. Thanks.
Sorry about that. Without the information you couldn't make sense of it, when you didn't address it at all it felt like you had sidestepped the part of the post that showed a scenario outside what you were talking about.
Here's where I think the big difference is. There are times that, as a DM, I see the need to adjudicate the results of a skill roll I have asked for in order for me to properly fulfill the duty of the DM to describe the environment. The environment includes information that can differ based on your character sheet, such as Darkvision, passive Perception and passive Insight. This is not to tell the player what the character things, but to give the player the information that the character should get.
Sometimes, this information comes from other PCs. Including tasks they are doing that would generate a dex (stealth) or charisma (deception) if you were attempting against an NPC. (Or another PC at my table.)
Regardless what the player knows, the player may need these checks to know if their character knows something. This isn't for the DM to control the character, it's for the DM to do their job of describing their environment correctly so the player can then decide what to do.
The idea you stated before for the lack of roll was:
Since a player determines how a character thinks and acts, the outcome of a task made to influence how the character thinks is not uncertain. Therefore, there is no ability check. These are also not house rules.
We now have a case where the ability check is not to determine how the character thinks nor how the character acts, but rather to give the player the information their character would observe. So that the player can make an informed decision how to have their character respond.
It seems that means that it would be valid to make that ability check.