Believe me, I'd normally be right with you two on This Kind Of Thing(tm), but in this case...
[quote name=\'clemon79\' post=\'231078\' date=\'Nov 22 2009, 08:14 PM\']No, because the last year of a decade is the one that ends in 0.[/quote]
This would be true if the basic concept of "decade" lined up with "century" and "millennium" -- if we referred to, for example, "the 10th decade of the 20th century," which would be 1991-2000.
However, what we actually refer to is, for example, "the 1990s," which is literally the years that begin with "199," i.e., 1990-1999.
Thus, we're about to enter a new decade, the 2010s, and if Bob appears in 2010, it can correctly be said that he has appeared as host of "The Newlywed Game" in six decades: the 1960s, the 1970s, the 1980s, the 1990s, the 2000s, and the 2010s.
Of course, "six decades" cannot be equated with "60 years" in this case -- there, there's your sticklerness.
Edited: See, that's what I get for going into much more detail than Matt. If I hosted "Quizbusters," each episode would be 3 hours long.