A third of the sites say heck yeah, a third say no way and a third say no but don't leave it out for more than a few days. I grew up in a "butter in the fridge" family (or more often, "Parkay in the fridge") but last year, I watched a very earnest and convincing man in a white coat tell me butter can stay out indefinitely. Admittedly, Dad and I are not the right test subjects for a "butter left out" experiment, as we both have iron stomachs and have eaten some pretty...OK, REALLY...dicey things over the years and have been fine. So now I compromise...if I'm planning on using the butter (or Country Crock) soon, I'll take it out of the fridge hours before I need it, but it still usually stays in the fridge.
I did once leave some store-bought flavored butter on the counter for...oh, about two weeks. It stayed fine all the way throughout, or at least it smelled and tasted fine and didn't make us sick.
