You would do well to advise that customer that, despite any announcements from Chicken Little, the sky is not, in fact, falling. That saleman has done your customer a major disservice, in order to reap the benefits of a large commission. I am not saying that power quality is not real. But it is not always important to every situation, and it is not always worth spending money to correct. In some situations, and I strongly suspect that a farm is among them, power quality issues certainly exist, but they are so small as to be insignificant.
RFI, or "radio frequency interference," is not related to power quality in a home (or farm) electrical distribution system. It is not created by a 60 hertz power system, and it does not impact a 60 hertz power system. It absolutely does not, Not, NOT "build up over time." The notion that it is RFI that is causing harm to animals, and that it is a problem with the power quality of the electrical system that is creating RFI, and that spending vast sums of money to improve power quality will save the animals from future harm, is, in my opinion, criminal, a scam, an attempt to "steal" money from unsuspecting and trusting victims.