I think everyone knows that if you insist on cursing, you shouldn't yell out "f**k you!" in the middle of a preschool or "you b***h!" in a house of worship. As the creator of Bleep!, I hold that all alternatives to bad words (e.g. shoot, crud, etc.) are acceptable to use. They are. However, even alternatives have their time and place. A friend of mine pointed out that when I yelled out "what the heck?" in the middle of the school lunchroom, it might not have been the most appropriate place to use any word in that vein.
I'm not trying to say that it was inappropriate that I used that kind of word; I'm just saying that you (and I) have to remember where we are at all times. It's not so appropriate to say "what the heck" to a teacher or in school; it's not appropriate to say "oh, pooh," in the middle of religious services. If it's a choice between an alternative and a real word, then hands-down no question, use the alternative. However, bear in mind that while words like heck and crud are appropriate when you're among friends, they may not be in certain other situations.