The last time I was in an Apple store I was in Seattle getting a MBA battery replaced. The Apple employee told me there were indications of water exposure but

The last time I was in an Apple store I was in Seattle getting a MBA battery replaced. The Apple employee told me there were indications of water exposure but no apparent board damage, so the humid Seattle air was probably to blame. Thankfully for me, they didn't refuse to replace the battery because of this. But that experience leads me to believe those water indicators are considerably more sensitive than the electronics themselves. If I had gone in there complaining about some weird issue instead of simply wanting a new battery, would the lack of apparent corrosion on the board still lead that Apple employee to conclude that the board wasn't water damaged?