My sons and myself often have bloody mucous/nasal discharge when
sick with a
cold. The green/yellow mucous is indicative of pus being present. That makes the possibility of an infection real such as a sinus infection. Sinus infections are not contagious as they are the secondary infection after a virus (which IS contagious). However, often I have gotten that thick, yellow/green mucous at the end of a cold without infection.