The good thing about terrorists - if there can said to be one- is that while they are highly motivated, they are not very bright.

This seems to be the case of the 2009 Christmas Day underwear bomber, whose plot to set-off off an explosive sewn inside his pants, failed in part due to the fact he had worn the same clothes for two weeks...

Such thinking was also evidenced by the shoe bomber in 2001, who took a stroll in the rain the night before his failed attack...