So, someone just told me to fuck off because my answer to their "Do you think I'm pretty" was "Of course, everyone is".

Sometimes I wonder if me liking everyone devalues my opinion of people ?

Pretty (lol) sure that's bullshit tho. "Pretty" is a meaningless subjective concept.
I don't find you "pretty", I like your appeareance, for various reasons.
I'd gladly tell you what catches my eye when I'm looking at you, but if you're looking for some universally accepted kind of praise, I'm not the one you should look up to.