lol, I was cooking dinner for a couple of people at my house a while ago and I sevred up the first two plates, went back into the kitchen to grab the next two and as I was finishing saucing them I heard the pepper or salt grinder going...
I shout out something like "TASTE IT FIRST!!"... as a joke and stroll back in to see the girl looking well embarassed and admonished....
It does annoy me, but hey, if that's how people like their food, then fair enough. I go really condimental when someone complains its too salty AFTER having liberally sprinkled the stuff over their dinner.
The best way I've found to avoid it is to not have salt and pepper on the table. This forces people to try it first, then they know if they really want salt and pepper and will ask for it.