I'd say that personal ketchup should be in the fridge, as I don't go through it fast, and it's liable to sit there for who knows how long. Diners go through it by the gallon, and leaving it out only means it'll be open and exposed for a few hours before it's gone.

Strangely enough, it seems all the restaurnts in california have changed to plastic ketchup bottles in the last six months. I think it's some health regulation, but I havn't investigated...

Matthew

PS: Butter in, because there are only two people in my appartment and we don't go through it fast enough. But more than two people, leave it out so it's spreadable.