Everything matters. And, as having a guitar that is a total icepick is as adorable as having a total mushmelon, the total system is usually thought to sound "good" if it produces much midrange, painless highs, and at least initially clear lows. The frequencies we "like" have to do with the evolution of the human ear vis-a-vis survival strategies, but that's a big bucket. Tommy liked the way TIGERS sounded, but poor Tommy had no children...
For example, it's semi-reliably reported that the "Beano" tone was not just a decent 1959 Les Paul and an early Marshall, but a treble booster too. Because Eric Clapton had ears, and the engineer used the right mike, and the mixer EQ'd it well, it sounded "good." And Jimmy Page used a trashed-out Tele through some pretty weird amps for the first few Zepp albums, and even in bits and pieces thereafter ("Stairway" solo) but he had been working in studios for several years at the time and he made some choices about mikes and microphone placement and EQ that are admired to this day.
And if you were in high school in America at any time in the past 50 years, you know it was a differently-but-still-imperative survival strategy to learn to like the sounds that everyone else told you were great - that's largely what high school does, besides teaching you that getting up at some godawful hour to go do a bunch of dumb bullshit was about the best you could hope for the rest of your life. So even if you though blues songs were really stupid, Van Halen & AC/DC belonged in the KISS bin instead of the ZEPPELIN bin, you still learned to associated those sounds with your first girl, your first drunk, driving around acting ridiculous, and when you later referenced those sound against the sounds favored by listeners to Marilyn Manson & Captain & Tenille & Cannibal Corpse & Barry Manilow, you knew yours were inherently better because YOUR BRAIN HAD BIOLOGICALLY MUTATED. As had theirs.... For god's sakes, there are actually GROWN MEN who listen to MADONNA because MADONNA very craftily figured out that if she sang like a ten-year-old girl, ten-year-old girls would want to BE her. Craftily, because she realized that ten-year-old girls would soon enough BE fifteen-year-old girls and fifteen-year-old BOYS would soon enough learn that listening to dirty MADONNA songs while with a fifteen-year-old girl was a survival strategy unto itself. And now, they CAN'T stop listening to MADONNA - just as she intended all along.
Alas I drift. I can think of at least a dozen ways to tame an overtly keening tone, because I sort of have to, I do like my treble....the big fat high-grade Belden & Mogami cables that transmit a powered microphone signal with great fidelity can swallow your puny little passive pickup's sound, while a very low-impedance cable like the Lawrence or George L's can assist a Telecaster into a 180-watt Super Twin Reverb shatter teeth. Yay! ~ everything is compensatory. If you ever plugged your guitar straight into a real 1000 watt PA with ceramic tweeters and horns you'd soon learn why that flappy, gasping Celestion Classic 30 had been SAVING YOUR ASS all along, as true treble is a force to be reckoned with. Go look at a guitar speaker's output curve sometime.
