I partly agree and partly disagree with Argo. While from an idealistic and ethical POV it definitely shouldn't matter, in reality sadly it often does, afaik theories indicate causes lying in appearance being unconsciously linked to health, don't know if it's backed by research, haven't looked into this before.
It's a difficult question. To begin with, even if many people would view person X to be '"ugly", others might not, sometimes even to the contrary. Also true for "beautiful".
Asking someone presents them and you with a problem in the case that they would personally dislike your appearance, because they would mostly be empathic and know it would hurt you, so they would try to evade it with euphemisms, so you would be none the wiser.
I once asked a related question online anonymously with photos supplied, I don't remember where, something like reddit. Now that comes with other problems. If it's anonymous, there will be people, and a lot of them, who get off on bullying, and they will say anything that hurts you. Especially in anonymous places, which appears to be logical. The difficulty would lie in staying rational and calm and filtering those out, also being aware that you're getting a population sample that might not be representative at all either, and being aware that, like stated above, there might still be people who would think differently than those who respond, to different extents and in varying numbers.
If you already struggle with ideas of being "ugly" or undesirable, you will also be biased and it will be next to impossible to avoid your mind jumping to the interpretations it's expecting or fearing. You could be pretty to someone and they could say "you are pretty", and you would find something that you would view as indication or even proof that they're lying, or misjudging, or whatever. So the being rational and filtering plan goes out the window. Even if you can uphold it for a time, your fears will come back at later times to haunt you.
I'm not quite sure if the results of such an endeavour would be constructive or beneficial for you. What is the purpose? What are the consequences? How influencial is it, given the probability that there will be people who will disagree with the majority?
Also, if you're in doubt yourself already that it truly is bad, I have doubts too.
And, there are people who would love you despite finding you unattractive physically. While that is not so common, it does happen, and then we are finally down to the most important thing: your mind.
A beautiful person who bullies people, abuses their partner, commits crimes, idk what, I think most people will agree that this is damn unattractive. So beautiful will not prevail automatically always.
Beauty will also fade with age, so what keeps people together is entirely other stuff.
So I guess there is no final answer, because most probably there will be different opinions and if the concern is about human connection, that will depend on the circumstances aswell.