If you see moldy parts of hard cheese (such as Parmesan, cheddar or Swiss), it is safe to eat it after removing the moldy portion at least about an inch around it. But watch out and beware of fuzzy -dd-colored spots on soft cheeses like goat or cottage cheese, as well as for yogurt and fruits. Molds of blue cheeses are safe to eat but go by the use-by date.
While pinkish poultry or meat can actually be considered thoroughly cooked, while browned beef and white chicken could be too undercooked, color and texture are NOT reliable ways to tell if they are safe for E. coli or salmonella which cause flulike symptoms.
The only way to tell it is by using a meat thermometer. In order to kill bacteria cook any poultry to a 165F heat; 160F for pork and ground meat and 145F for steaks.
You can still safely refreeze them as long as they have still ice crystals or at least haven't warmed to higher than 40F. It is safer to thaw them in the fridge as it takes longer than leaving them on the counter, so if you plan to cook them the night before, transfer the meat from the freezer to fridge. If it happened you forgot to refreeze it that day, it should only be good for 1-2 days in the fridge.
Milk if properly stored should be safe to drink for 5-7 days after the sell-by date. This is the last day the store should display them. But once it reaches your fridge, follow the use-by day which is the last day the item will be at its optimal taste and texture. If it smells sour, toss it away!