Sorry, Shakespeare. But this phrase from Hamlet comes to mind as I've been reflecting on the nature of false modesty.
Actually, I've learned quite a lot about this particular affliction from up close, personal contact with it. And what I've finally realized (maybe a little late) is that someone that "doth protest too much" is really masking a naked, ugly, overwhelming arrogance.
False modesty is an especially effective mask for arrogance. In cultures where arrogance is both endemic and therefore taboo, false modesty is the cover up. With false modesty, a guilt-ridden society can appear reformed while endorsing culturally impermissible arrogance.
False modesty is the sedative for arrogance's cutting blade. False modesty trades on apparent sincerity, lulling victims into an early trust. Once sedated, the cutting can begin. Then, the sudden personality bait-and-switch reveals penetrating aggression. Like a snake that paralyzes the prey before eating it, false modesty transfixes people.
The unmasked lie only makes the aggression worse. You end up recoiling at two things. The lie of false modesty itself. And worse, you are repulsed with embarrassment at the arrogance laid bare.
Now, when I hear people deny expertise they clearly want, my guard will be up. Way up.