I'm curious more than anything and trying to figure out the logic of it. The majority of things on this thread are offensive for obvious reasons (germs, rudeness, general disgustingness). But I don't understand the buttering the bread/roll thing.
I just want to know what bothers people in buttering the whole piece of bread/roll and taking bites of it,
other than that it is an official etiquette rule. Most etiquette rules make some sense to me, even if I don't always take heed of them all. But this one doesn't.
One person may have indicated that they don't take a bite of anything ever and put it back on the plate and are disgusted if someone else does so in front of them. So if that is the issue, then I can see how it might gross them out (which would be like me having to watch someone slather mayonnaise on something and then watch them eat it

). So if it's a gross-out thing I see why it might be a major pet peeve. But for some people it sounds like it was just ingrained in them so much as a child that it has become an obsession - like the elbows on the table rule that is part of the fun and joking at the '50s Prime Time.