"Frauds" who are still genuinely good at what they do

Hercule Satan (DragonBall): Claims to be the strongest fighter in the world. While he doesn't match up to the Z Fighters, he's still a skilled martial artist who can beat most people on Earth with relative ease, and was even able to avoid some of Kid Buu's attacks

Faust (Project Moon): Claims to be the smartest of LCB, and perhaps one of the smartest people in the City. Turns out a lot of her feats come from the fact that she has a group chat constantly feeding her inside info relevant to whatever mission the Sinners are on. She's still able to think her way through a vampire attack when she gets cut off from the group chat, but she is sloppier and takes more time to come up with plans. Still, she's good enough at what she does that if it weren't for Yi Sang correcting a minor detail in her explanation for how Warp Trains worked, none of the Sinners would've noticed anything was off