My ex husband didn't cuss -- at least, not until I stupidly corrupted him (I have a terrible potty mouth and it's a long story). We knew this was completely sincere and not some sort of affectation because when our oldest son accidentally stepped on his dad's junk once when his dad was in a dead sleep on the living room floor, he woke up making cartoon sweary noise (a la "rassum frassum mrrrfff").