I can imagine this happening in template code:

    template <typename T>
    bool isNumberInfinity(T number)
    {
        return isinf(number);
    }

    template <>
    bool isNumberInfinity(Number number)
    {
        return number == Number::INF;
    }

So instead of specializing ints, we rely on isinf working for ints, instead of doing the "correct" thing:

    template <>
    bool isNumberInfinity(int number)
    {
       return false;
    }

This is a very contrived since I'm using template functions, which are practically useless, but it holds for any data structure which holds a type that is meant to behave somewhat like a "number".