I guess it's an acquired taste. My mom could easily tell the more expensive coffee. Not me though
Exactly - you have to drink enough of it, black (if you're drinking with milk and sugar of course it tastes mostly the same). I can absolutely tell the good stuff from the bad (and probably how it was made).
The big things really are how it's roasted, what grind you use (how coarse), what you use to make it, and yes, what beans you use, but those only matter if you do the first three right. Roasting is a big complex thing, but one secret is that properly roasted very dark beans are actually much
less bitter than 'normal' coffee.
For making it there are four main ways that will give you a good result: a pourover, aeropress, french press, cold brew. The aeropress is neat because it's almost impossible to mess up - guaranteed good results every time. The pourover is of course popular recently, but it's not just a matter of pouring it slowly, there's tons of technique there to get it right (like making the water the right temperature, not boiling). French press is probably the hardest to get right. Cold brew is its own thing. And for each of these methods you have to grind it slightly different for best taste - aeropress wants a fine grind, french press wants a coarse grind.
But the other dirty secret is, that like wine, beer, meat, basically everything else,
the expensive stuff is not necessarily the same as the good stuff. As usual the cheap crap is usually meh, but there's no guarantee a $30/bag coffee will be better than a $12/bag coffee. It might just be $30/bag because it came from somewhere more remote, so it's a novelty. I've also had the kopi luwak (the expensive stuff), and while I didn't have control over the roasting, I can't say it was any better than the $15/bag from a good local roaster. So you're just paying for the novelty.
Basically, they could easily do an obsessive coffee manga with an MC who has the Aeropress of God like they do with the bartending