This. And I'll also add that until I was required to try each variation of a certain coffee for a job prior bring it to stores, I was convinced there was no such thing as coffee that's not bitter. All coffee I'd had before tasted like chewing on aspirin[1].

For the job, there were five "espresso style" variants[2]. Although the "black no sugar" was too intense or me, none of them were bitter. I could make them bitter if I left one open too long or by heating one and letting it cool. There are only three variants now, and I miss the the discontinued "black lightly sweet" and "mochachino".

I've since experimented with making cold brew, servedhot or cold, with a little potassium bicarbonate. I've also tried some ready-made cold brews and lighter roasts. Darker roasts taste more burnt to me. Robusto is unsuitable. Arabica is better, especially if it has a good proportion of Kona in it. If it doesn't specifiy how much Kona, assume it's not enough to make a difference. I haven't tried pure Kona, even while in Hawai'i, because price.

[1] This was not planned. I was mistakenly given regular tablets instead of children's chewable…more than once, by different people. Not a recommended experience.

[2] I'm told Italy made them stop calling it that, because of some legal definition of what constitutes espresso.