Nowadays, anyone with access to the Internet can call themselves reviewers, but honestly, I'd say only about 1 in 10 "reviews" I read are TRUE, professional reviews. I was chatting with a Marvel exec the other day, and he was remembering how he reviewed some comics of Dale's many years ago. He said just how embarrassed he was about those old reviews, and how unprofessional they were. And those reviews of his, in my opinion, were leagues ahead of what we read these days. Most reviewers today don't even seem to know who does what, for Pete's sake!! They'll blame or credit one member of the creative team for something that had nothing to do with them, and vice-versa.
As for the word serviceable (re: your comment on another thread), it bothers me because of its dismissive nature. What if I said "Michael Jackson's music is serviceable," for example? Is that accurate? No, of course not. I think we can agree that he is recognized as being talented and has proven himself over a span of many years. I can say "I've never enjoyed that type of music, so this song doesn't do it for me." AH! Now that's fine. So when someone who obviously likes more cartoony art says that someone more realistic "sucks," yep, I have a problem with that. A reviewer should be well-versed in all types of art and be able to recognize an artist's strengths and weaknesses WITHIN that genre.
If you look more closely, by the way, you'll see there are many reviews on which I don't comment. They can be negative reviews, as long as their criticisms are legitimate and supported by evidence.