There is a law, Title 4 of the US code, that specifies what constitutes respectful display of the US Flag.Â http://www.ushistory.org/betsy/flagcode.htm
It is comprehensive, it is Law in the District of Columbia,and it is the custom to obey it.
Active Duty Military personnel, in uniform at ceremonies where the Pledge of Allegiance is recited, are to REMAIN SILENT and render a hand salute to the Flag while the recitation continues.
The flag is not to be worn as clothing.
The code is straight forward and violated all the time,.mostly by people who SHOULD KNOW BETTER.