You can only trust your ears if you have good ears and know what to listen for. Otherwise it can really be helpful to take advice and direction from others.
100% agree. The advice that one has to "listen for themself" is true enough, but as with a lot of other things in life, one can get better at listening. And there are better listeners out there than me -- by seeking them out, I've gotten better at doing something which seems simple, but it's not. That why this is a hobby and not just a place where people come to just blurt out that something "sounds good to them." There are criteria, specific things to listen for and notice, judgments to be made. In the end "it's up to each listener" is true, but it's a simplistic truth, which barely needs saying.