Example of Nullable type hurting innocent puppies.

BadChickenReview.cs

public class FoodRating 
{
    public int? Score { get; set; } // YAY, let's make it Nullable!  Is this even valid?
}

public class ChickenReview
{
    private readonly FoodRating _rating;

    public ChickenReview(FoodRating rating)
    {
        _rating = rating;
    }

    public bool HasAboveAverageScore()
    {
        if (!_rating.Score.HasValue)
        {
            return false;  // WTF???
        }

        return _rating.Score.Value >= 5;
    }
}

BetterChickenReview.cs

public class FoodRating 
{
    private int _score;

    public FoodRating(int score)  // class can't be in an invalid state.
    {
        _score = score;
    }

    public bool IsAboveAverage()
    {
        return _score >= 5;
    }
}

public class ChickenReview
{
    private readonly FoodRating _rating;

    public ChickenReview(FoodRating rating)
    {
        _rating = rating;
    }

    public bool IsPhenomenal() // encapsulate what matters inside, expose what matters outside.
    {
        return _rating.IsAboveAverage();
    }
}