Va. Code Ann. § 22.1-183

It is unlawful for a school bus licensed in the Commonwealth to be operated on the public highways of the Commonwealth for the purpose of transporting persons or commodities other than school personnel, school children, elderly individuals, or individuals with mental or physical disabilities unless the lettered identification and school bus traffic warning lights on the front and rear of such bus are covered with some opaque detachable material. This section shall not apply to any such bus when operated by a salesman or demonstrator in connection with a prospective sale or delivery of a bus.