Pro Reviewers...?

Rating: 10/10 (5 August 2014)

I look through some of the metacritic reviews and they leave me wondering what a person has to do, what degrees or credentials are needed, to be a pro reviewer.
I was no fan boy going into GotG, it was never on my shopping list back when I was reading comics. But I found this movie to be fun, entertaining, and engrossing in the sense that I was enthralled with watching the characters interact. I personally thought that for a first GotG movie it worked in good character background and development, and loved that there were those moments where you either laugh out loud or nods your head in a sudden glimpse of understanding about why they do what they do.
That said, what I don't get is why some reviewers fail to even do a google search on what the comics were about before writing their review, or heaven forbid, before viewing the movie so as to understand it in context.
Instead I see hugely negative reviews, no not all the reviews but quite a few, by people who are clearly ignorant of what they are even watching. I get that they want to be heard, but trashing a movie which is clearly a hit in order to draw people to your article to find out why you hated it, is frankly childish and purely self-serving. No one says that as a reviewer you must like a movie, if it is not a movie you liked or a genre you appreciate, it might be best to clarify that. If I see a movie I don't like and I tell a friend about it, I always clarify the reasons why rather than simply trashing the writers/directors/actors/etc.
Perhaps I am wrong in my assessment. I don't expect everyone to love this movie as much as I did. However, I do expect professionals to provide me with clear and solid reasons for not liking it. Even if it is just to say that it wasn't their kind of movie or they dislike comic movies or they dislike sci-fi.