These are good (albeit mostly intuitive) reference checking tips. What amazes is me is how rarely anyone bothers to check references. I've been listed as a reference many times, but estimate I've been called much less than 10% of the time. That's probably because it's a pain to do this, and many companies won't give you helpful responses (and it may be that no one cares what I think), but all this suggests to me that the most important reference checking tip is to do it.
True on the best hack being to actually DO referencing.
That said, I thought the non-intuitive hack here was the trick about contacting the references and asking them to call you back as a sign of their view on the quality of the potential hire.