On a Philosophy Forum someone asked, “What makes a good friend?” along with a quote, “A friend for all is a friend for none”. So here’s my response:
A good friend? It’s a formula involving your tolerance of the ways they piss you off. Bad friend is one who goes over a particular line. Good friend will still piss you off, but it’s in ways within your tolerance zone.
You can be a friend to all but of differing degrees.