I myself can cuss a blue streak but I was still taken aback by swearing in NZ. It may be the delivery or the connotations, or maybe the casualness of it. Even in dive bars in the US I'm used to a man apologizing when he realizes there are women present after he's used colorful language. It's not that I mind swearing, it is simply a shock. Also there is one word in the US that is generally considered the worst/dirtiest word of all, the dreaded "C" word. I heard it A LOT in NZ, though not in the same context it would be used here. Every time though, I'd cringe; it takes a while to lose one's cultural conditioning.
It's simply another thing to become accustomed to.