Had one the other day. Service rep had looked at this guy's device, was clearly liquid damaged - appeared that salt water had come into contact with it from the amount of corrosion on the main board.
Guy comes in to pick it up, I explain the device is clearly liquid damaged and he would have to go through insurance for his replacement. The customer then began one of the more pointless arguments I have ever endured... the story changed several times... and it just got better and better.
CS: The phone never got wet.
Me: The corrosion on the main board is conclusive evidence that the device has come into contact with some sort of a liquid... this appears it might be salt water.
CS: Let me tell you something... I'm an aviation electrical engineer...
Me *Oh sweet Jesus...*
CS: ... I know what corrosion is. Water cannot damage electronics.
Me: If you dumped a gallon jug of water over the instrument panel in one of your planes you're saying it wouldn't cause any damage?
CS: No, water doesn't damage electronics. I would know, I'm an electrical engineer.
Me: To pacify you, I'll double check with a technician [Addressing one of the technicians] does liquid damage phones?
Tech: Are you seriously asking me that?
CS: You don't need to be a smart-ass, I'm telling you that liquid cannot damage phones, and this phone has never been wet.
Me: Ok, what liquid came into contact with the phone then?
CS: None! JUST GIVE ME MY PHONE I'LL GO SOMEWHERE ELSE! I want it in writing you won't fix my phone, so when I go somewhere else and they prove it isn't damage I can sue you!
Me: That information has been noted in your accout.
CS: FINE! Oh, and for your information water isn't a liquid.