There are some things that aren't appropriate to do. Jim Croce once sang that you "don't spit in the wind" or "mess with the Lone Ranger." I would like to add another item: You don't sing or play your own interpretation of our National Anthem. "The Star Spangled Banner" represents the United States and should be sung or played with the utmost respect. I know it is a hard song to sing but, when someone like Roseanne Barr butchers it purposely as she did at the San Diego ballpark in 1990, it shows a complete lack of class.
Prior to the 1960's, the Anthem was always played or sung in the manner of the Mormon Tabernacle Choir or the Marine Corps Band. In 1968 pop singer Jose Feliciano started the trend of changing the interpretation of the Anthem at a World Series game in Detroit with a bluesy, slow rendition sung and played on guitar. I don't think Feliciano meant any disrespect but the response was extremely negative. It was just too different from the norm. However, it started the trend we see today of various artists doing their own thing with the Anthem.
At Woodstock in 1969, Jimi Hendrix did a slow, controversial, screaming, guitar version of the Anthem which to this day not many people understand what he was trying say. Maybe it was some sort of good-bye to the flower child '60s as he was dead within a year afterward. The rock group Aerosmith botched the words at the Indianapolis 500 in 2001, Robert Goulet did likewise at a boxing match in 1965, and Olympian Carl Lewis botched the lyrics and the tune in 1993 at a Chicago Bulls basketball game.
"The Star Spangled Banner" is played at almost all major sporting events. Usually the current year's latest popular singer is brought out to sing it. It is considered an honor to do this and regardless of if the person is a rock, blues, or soul artist, they should put that aside and sing the Anthem as it is intended: with respect and without an interpretation from their genre.
The great singer Nat "King" Cole once said "If you want to ruin your career, just try to sing the National Anthem at the ballpark." That may be true, but if you must sing it, at least learn the words, rehearse a lot, show respect, and do your best.