Doc
You are correct that in most states to be convicted of indecent exposure the prosecutor has to prove some sort of intent by the person doing the exposing. usually the intent to alarm or titilate ( what a great word)

But a Conviction and arrest are two different things. Convictions come as a result of a trial and/or a plea in front of a law trained judge. Arrests depend on the police officer, who has a wide latitude in most situations, and the circumstances.

For instance an inadverant flash in front of an all girls catholic high school is likely to result in an arrest and probably a conviction An inadverant flash on the highway changing a tire will probably not get you a ride in a police car.

A couple of years ago I was watching a parade with my friend and his wife, we were standing next to a cop. One of the kilted marchers had had a bit too much to drink and fell over revealing his secrets to the world. My friends wife just started laughing and said "Well that answers that question." He did not get arrested and continued the march and the cop never batted an eye.