I apologize for airing my opinion so forcefully earlier. I've removed my dumb post and the rebuttal. I'll keep my personal opinions out of public forums from now on.
That said, I do remember reading in the past that the rate of head gasket failures has been declining in recent years. Maybe the changes they've made to the bolts and block threads has improved the situation. Either way, cooling system maintenance is key to prevention, but it's not 100% foolproof. The vast majority of Northstars never have the problem, but unfortunately a small percentage do have a head gasket failure even with perfect cooling system maintenance. Mechanics know how many of them fail and which years are worse just as much as a shoe salesman does. The only true statistics would be from GM, and they certainly aren't sharing.