There are just some people that are perfect for being a conman as they have this smoothness about them that just comes across naturally. So, with that in mind, how about this for potentially being the smoothest conman that has ever existed?
Back in 1935, Victor Lustig was arrested for selling people a machine that he referred to as a currency copier. It was said that it allowed people to print their own $100 bills, so it was clearly going to be rather popular among people. However, that was not the smooth part that is connected to this story.
This was the same guy that had previously managed to sell the Eiffel Tower to a scrap metal merchant before running away with the money. Even after being caught he was still smoother than you could have ever thought possible.
When in jail, it turns out that he took bedsheets and turned them into a rope ladder. After climbing out of his window, which was on the third floor, he then casually pretended that he was a window cleaner and would wave at the windows as if he was indeed washing them. Even as he dropped lower he would continue doing this and apparently countless people saw him but nobody thought that there was anything untoward going on. Eventually the police went to get him from his cell in order to take him to court only to discover that he was gone.