For a date range greater than one day the total number of Unique Visitors is greater when I exclude pages ending in "foo" than when I look at all pages. The difference is ~4%. Why would this be happening? For daily totals of Unique Visitors the difference disappears and there are slightly fewer Unique Visitors when I exclude pages ending in "foo".
Related to this, What is the difference in applying this through Advanced Segments vs. Filters? They both show subtly different answers.