I had been wondering for quite some time now how/why I would have to manually reset an objects origin after applying all transforms. Problem answered with this video (125) Turns out applying the location transform moves the object origin. Good to know!
Then the centre is located in the world (0, 0, 0).
Most of the time this is unwanted behaviour for the most objects.
Applying scale will solve many problems. So people will use that one most of the time.