It doesn't matter much to me so long as the parent doesn't abuse them or use them is frivolous context. My parents cursed in front of me all the time when they were expressing how angry they were, such as, "you damn well better ****ing clean your goddamn room, son!!" To this day, while I curse a fair bit more than average, I usually do it to express anger, sarcasm, or some other emotional extreme.
But when I see parents in public with their kids using curse words in contexts like, "$5.00 for a slice of pizza? Oh, hell the **** no!!", it makes me a little sad for the kid to be honest...