Curse words are absolutely valid in dialogue, just like poor grammar. The best two-pronged rule is dialogue either has to 1) sound the way people talk, or 2) be entertaining in its disconnect from the way people talk.
Good to know that aiming for the mid ground would be a mistake! In this case i'm going for number 1. At least I hope I'm headed in that direction...Thanks!!!
Thank you for your comment! I will love it and hug it and pet it and call it George. Or, you know, just read and reply to it. But still- you rock!