This is all the official verbiage you will find about how to wear the Scout neckerchief – anything else you have heard is urban legend.
From the BSA Insignia Guide :
Boy Scout neckerchiefs are optional. The troop decides by vote, and all members abide by the decision. If the neckerchief is not worn, then the shirt is worn with open collar. Boy Scout and Boy Scout leader neckerchiefs may be worn in a variety of plain colors and contrasting borders. Those available through Supply Group include the embroidered universal Scouting emblem if perma-press, or printed if not. Troops choose their own official neckerchief.
Local councils may prescribe the specific official neckerchief to be worn by Boy Scouts and Scouters on a council or district basis.
The neckerchief is worn only with the official uniform and never with T-shirts or civilian clothing. All members of a troop wear the same color.
Special neckerchiefs, the same size as the official ones, may be authorized by local councils. Such neckerchiefs may include identification of the chartered organization. The standard designed neckerchief may be personalized with troop number, city, and state. By troop approval an Eagle may wear an Eagle neckerchief.
Neckerchief slides. Several official slides are available from the Supply Group. Boy-made handicraft slides also may be worn.
How to Wear the Neckerchief