In the 'old days', the only people who commented were geeks. Now, everybody comments, good or bad, useful or not. That is why it's nice that some retailers include the option to comment on the reviews. Enough 'thumbs down' and the useless review is hidden, still there, but not something you have to go over unless you feel pressed to read everything.
Keep in mind that I even take professional reviewers with a grain of salt. They are commenting on something new out of the box. Not something that they've actually used for awhile. Ok.. the new Iphone is expensive. But will it still be working 3 years down the road? (yes) I'm happy to spend more on something that isn't going to fail the moment it wings out of warranty OR that has features that I will be using (a non-businessperson).