Mixed woods means they can use anything they have available. I prefer to go to my local restaurant supply and get Mesquite or Oak charcoal. I'm paying $15/40lb bag.
That way I know what flavor I'm getting. I also get all my wood there.
BigB's BBQ - WSM 22.5 - Webber Q 120 - Santa Maria Grill - Grand Turbo 52 NG