A con man is a clever man who acts to get things. Like selling faulty equipment. A crook is an older term, just being like a low level thief. A culprit is the person who is to blame. This can be for a thief or other crime. A scoundrel doesn't necessarily commit robbery, but is dirty and creepy. A street kid who annoys a shop clerk can be a scoundrel. EDIT: A rascal is like scoundrel, but more annoying and less dirty. A kid who is mischievous and gets into trouble is a rascal.

Tiger, what a good question! Con-man is not specifically interchangeable with any of the others. A con man cons you out of your money through guile and deceit. He may well be a rascal and a scoundrel, but those words do not describe what a con-man does. A rascal and a scoundrel are fairly interchangeable. Both mean a disreputable person. A culprit is someone guilty of something, so cannot be used interchangeably with the above at ALL. Whilst crook simply means someone who is a criminal - commits crimes