You obviously don't know How The World Works. Employers routinely violate the rights and breach the law regarding employees. Employees can fight back but it is usually an uphill battle with the legal costs risk higher than the reward, then they are left in an employment environment they don't want to stay in and expecting a good reference is then futile.

Businesses generally do a risk analysis on these kinds of practices, deciding if it benefits them more to push or exceed the legal limits, versus the few downtrodden employees who will fight back against the hand that feeds them.

However, I suspect the person was making up nonsense about actually being penalized (versus a mere myth perpetuated by a rogue manager), but did have a good point that in many cases if there is water ingress it is not hard to spot in other ways. Generally there is a fine film of solder flux remaining on circuit boards and it is water soluble, WILL definitely leave an irregular (salt) pattern change visible compared to the adjacent area. I don't feel bad about this though, because if water actually does get inside, the warranty really should be voided if it subsequently starts to malfunction.