I'm not aware of any issues with static buildup on devices. If you're using shielded cable, you should use shielded connectors and ground the cable.
My guess, without seeing pictures, with that one install is that water is wicking down the cable somewhere and damaging the switch - EMI interference wouldn't be resolved by plugging it into another port.
Yep, I would use the shielded connectors and connect the drain wire on both ends. Plugging into the switch connects the shield to the switch ground.
The misbehaving install's switch is in a cabinet inside a building. There's no water anywhere near it. And it's located in rural Vermont, which I don't think is a high EMI environment. Not near power lines or anything either.