When I lived in Jordan, it became very evident when it was damp or raining outside since you could hear all of the arcing from the horrible connections. I ended up with a motorized variac for my computer, and that would be racing from one end to the other or its range trying to keep the voltage within range (UPS's weren't readily available, and then you'd have to listen to the alarm almost constantly!).
I'm sure it's better now, but when I lived in Germany, I had one clock that used the line frequency to count time. On Friday afternoon, if you set it, by Monday it would be off a few minutes, and then slowly over the week, return to the 'correct' time as the day crew brought things back. At least things didn't arc, and the voltage stayed consistent, but you couldn't count on the frequency!