I also work in an electrical engineering (not household stuff) and generally it is pretty obvious if electronics have been subjected to significant over or under voltage (or current) conditions that damage components. It does take some detailed knowledge of the particulars of the system design (not just the circuit diagrams) and may require test capabilities not usually available to the "Geek Squad" members. I also suspect the effort required is high enough that most companies won't bother making the effort unless you are trying to get something really, really expensive replaced.

The other thing to remember (as ILBob pointed out) is that grounding is very important. A lot of the technology in surge suppressors is used for similar reasons in my field and I'll point out that even the best surge suppressors have limits and won't work if there are unprotected electrical paths to the device.

-Eric