Pet Peeve: Magical Masking
So you have some extra method of gaining information in a convenient, super reliable form.
Maybe you can Appraise the LitRPG character sheet, or use a power detector to measure their power level and shoe size, or maybe you can just sense energy and recognize people and their health from miles away!
This is all awesome, but unfortunately your OP MC has the Super Special Snowflake Power: Napkin Folding.
Obviously if anyone knows they have the dreadful power of
folded napkins, then the government will send a SWAT team to kick down their door, shoot their dog and nuke them from orbit... just to be sure.
So our plucky MC needs the ability to perfectly fool the perfect information system!
Luckily he just tripped over the Jock Strap of TMI which will conceal any napkin-related skills!
What a coincidence!
The first thing that annoys me about this is how contrived it is.
I mean, everything in fiction is contrived, but these special concealment tricks always seem more contrived than most.
They're almost always completely unrelated to the rest of their skillset.
It doesn't matter if their entire power centers around blasting their energy out like a supernova, they can always use the hiding technique flawlessly and without any significant disadvantages.
Furthermore, the stealth is often their
strongest technique.
They might be challenged by various antagonistic peers, but it would never do for their true power to be seen through by even the strongest people, those are the ones they are hiding from!
So they might have a bunch of high-level powers, then one super-duper-god-level power.
It sticks out like a sore thumb.
To make it worse, in most cases the MC doesn't even try to get it.
It doesn't fit the character to seek out the Assassin's Mask, so they have to stumble across it.
Often just before they need it.
And when they actually have a false persona, the author has to go out of their way to make them fumble it like crazy or the readers might be confused.
"What's your name?"
"Bob! Wait, no, I'm not Bob. I'm... let me see what it says on the note... 'Bob, remember that you aren't Bob, you are Not-Bob.' Right. So I'm Not-Bob."
"Sounds good to me."
I mean, would a person who is incapable of even
trying to lie, think of lying as their plan in the first place?
At least practice in the mirror!
The other part is the hypocrisy.
The entire reason the information/detection powers were added to the story in the first place was to make things easier for the Author/MC.
They don't have to fight the enemy (and be humiliated) to realize they are outmatched, and they don't have to prove their credentials to be trusted, they can just rely on the convenient and always perfect detection power!
Then they shy away from actually dealing with the consequences for themselves.
Not only that, but they almost never allow the other characters even the
possibility of similar skills.
Not only does the MC continue to use the information without verification, they never even consider the possibility that it might be wrong.
In a lot of cases the information is only useful if it's 100% reliable.
Once you start saying things like 99% of spies will be caught, but 1% will be completely missed, their policy of depending completely on it starts to sound bad, even if that's actually pretty impressive in RL.
And it never seems to occur to the other characters that they might need verification either.
After all, the MC needs to breeze by without any effort.
If they just stop all the people who they can't scan, it would defeat the purpose!
Ultimately it comes across as sloppy world-building.
They don't want to go into the details needed to deal with uncertainty, but they don't want to deal with certainty either.
The Masking feels like a clumsy patch, added later and carelessly applied.
