What's everybody's go-to answer/response when a customer asks about "dirty electricity"?

I work in a town that has a fun blend of ultra-rich folks and new-age trust fund hippy types. In the last couple weeks, I've had the rich folks ask if there's anything I can install to mitigate "dirty electricity" from interfering with their high-end appliances, but I've also had yuppies ask me if they're safe from EMF "rays" from the transformers (I think they're step-down xfrs) at hydro plant next door.

I've always wanted an answer or reply that will give me some internal satisfaction without ripping off the customer or being a complete dickhead by pulling out a can of duster.