The Advanced Search in the Domain Find(CTRL-F3) function allows you to select a custom Active Directory field(added by IT, not a windows default AD field). When you specify the criteria and value for boolean fields it recognizes the field is boolean and limites the search to true or false accordingly. When you press find now... the search results are empty. Since I cannot cut/paste the print screen, here are my Find Settings: Type = User, US Security Processing is the selected field, equals is the logical operator, and true is the value.
Additionally on Custom String fields it would be very helpful to have a Contains, Does not Contain logical operator in the Find function.