Those who have an innate understanding of and deep passion for the field in question. I've gone to animation and film school in addition to having played every game under the sun, so I can definitely say objectively whether a visual piece of fiction is good or bad.
You are completely wrong. Opinions are 100% subjective. Having an innate understanding of and deep passion for the field in question doesn't mean your opinions are "objectively right," it just means you understand and you're passionate about the field in question. Just because I didn't go to animation school doesn't mean I'm "objectively wrong" if I like some piece of animation you dislike.
Read this:
http://en.wikipedia.org/wiki/Opinion
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Full rap metal jacket ~ Method Man