> AFAIK everything above above absolute zero radiates, which effectively means that everything radiates.
What really matters is temperature relative to surroundings. Something at the same temperature as everything around it won't lose any net energy to radiation.
We can only talk about the surface. The surface emits basically no radiation at all. The amount of Hawking radiation it emits is practically non-existent. It's truly black.
The temperature inside could be anything. You could well be inside a black hole right now.
Even if we were inside one we couldn't really talk about the temperature of the singularity. The singularity is a divide-by-zero error. It probably doesn't physically exist at all, and whatever does exist is beyond our ability to model.
And black holes are much colder then their surroundings, i.e. the Cosmic Microwave Background. And they will be for trillions of years.