The melodramatic ones are especially tedious. There are the one-note sambas where everything 'sucked' (a popular descriptor). There are the reviews that look like they meant to submit it for the Bad Hemingway Contest but accidentally submitted it to the cruise website. I really don't mind the reviews that have negatives provided they are balanced with some good and don't get into a bunch of histrionics.
But as a general rule, I've found that people with an axe to grind over some little perceived slight are the ones who can't wait to submit a bad review. The happy cruisers often don't post reviews, but instead say good things in the message boards.