Metro should partner with corporate sponsors to maintain the stations, like Disney does with various pavilions at Epcot Center and the Magic Kingdom. Metro would get, for free, highly attractive and pristinely maintained stations, and the corporate sponsors would get a unique and effective public relations and advertising platform.
Metro stations are aging and rundown, unattractive (dingy walls, broken tiles, water stains), and poorly functioning escalators and turnstyles. If Metro allowed corporate sponsorships of the stations, the corporation's identity would be closely associated with the station, and the corporation would have perfect incentive to maintain the station in a pristine, operational, and engaging fashion. The model would be Disney, which has lots of facilities and pavilions sponsored by other corporations. Metro would get vastly improved stations for free -- might even generate revenue! -- and the corporations would get a unique and effective advertising and public relations platform.