Some persuasion checks are not meant to be completed. For example, if you try to persuade the troll in the bridge by using Strength, you will always fail, because you won't intimidate a troll.
While it does makes sense,...
Actually it doesn't make any sense to have multiple persuasion choices, and all of them are predetermined losing checks. That serves no purpose other than to give the player a false sense of control. That troll example is another pointless losing check, if it's not accompanied by other choices. Always-losing checks make sense only when there are other dialog alternatives that lead to different outcomes or different conversation paths.
In fact, more generally, it makes no sense to have all the dialog choices to be persuasion checks (losing or not) without any regular dialog choices.
The player should always have the option to NOT attempt to persuade an NPC. As long as there are always regular dialog choices, then it's OK to sometimes sneak in a losing persuasion choice as ONE OF THE CHOICES in the conversation. But this multiple persuasion-only all-losing choices is BS.
