1 Cottage cheese left out for three hours: “When perishable foods like cottage cheese are left at room temperature for longer than 2 hours bacteria can develop that cause foodborne illness.”. 2  Butter at room temperature: “…it will develop a rancid taste.”.he didn’t approve of anything: 1  Cottage cheese left out for three hours: “When perishable foods like cottage cheese are left at room temperature for longer than 2 hours bacteria can develop that cause foodborne illness.”. 2  Butter at room temperature: “…it will develop a rancid taste.”.