Yes, underneath the large-ish TV in the lounge, and then latterly next to a small 12 inch black and white TV in my room. The +2A lived on my desk in my room next to the new 14inch colour TV bought specially for it. The same TV was used for my C64 and, after than, Amiga. If they were better shielded, and sat next to a smaller TV, that might explain why they suffered no ill-effects.
Man, if that's the reason... I feel irritated with myself even now. Thanks for possibly solving the mystery.
The fun thing is that especially for the early C64's the reason they were better shielded was that Commodore had problems meeting emissions standards for them, and so if you open them up, you'll find RF shields like this [1] (from [2]).
Some earlier models had a foil-covered cardboard wrapping it instead.
I think later models reduced the shield to cover just a small set of components instead.
So they survived better because Commodore failed to figure out how to make them produce less interference.
Man, if that's the reason... I feel irritated with myself even now. Thanks for possibly solving the mystery.