It is unclear what you mean by "deception." Certainly some deception of the Jewish people occurred early in the Holocaust, as the Nazis pushed Jews into ghettos under false pretenses, and sometimes at the personal level. Many Jews bound for extermination camps, for example, were told they were simply being resettled, which had actually happened to many of them before, after World War I and during various pogroms. But the biggest deception of all was the way in which the Nazis stoked the anti-Semitism of the German people. This was done through relentless propaganda, using motion pictures, posters, radio addresses, and even children's textbooks to persuade the Germans that Jews were both evil conspirators responsible for all the country's ills after World War I and racially inferior beings that ought to be destroyed. As for whether such a thing could happen again, the unfortunate truth is that it has happened again. Governments have stoked ethnic and racial hatred in an effort to promote violence against minority groups multiple times around the world since 1945, and the result has, in some cases, been genocide. Cambodia, Rwanda, Bosnia, and Darfur in Sudan are just a few regions that have witnessed the mass murder of minorities or so-called "enemies of the state" in the last 60 years.