I think that the key is to "consider the source" when reading opinions. If the source is the editor of a respected magazine, chances are his opinion are more valuable than the disgruntled user with an axe to grind. Most are probably somewhere in between. But that's just MY opinion!
The problem with gun magazines is that you seldom get a bad review, and even when they mention negatives they often gloss over them. A crank (or a series of cranks) may actually be willing to provide a "real world" truth about a firearm vs. the cherry-picked sample known to work with the writer's favorite ammo.
Old Dude wrote:
When I read reviews at, say, Amazon.com, I always read the negative reviews first. What is it that people don't like about it? Is there a pattern to their dislike? Are the problems they encounter something that is likely to matter to me?
Only afterwards do I read the positive reviews.
This is a good tactic. I think it's best not to think of individual opinions on the internet, but to look at both the quantity and any recurring likes or dislikes about a specific product. It also helps to think critically about what the complaints are -- there may be a lot of complaints about a trivial aspect of something, while the main features may be OK (eg, Glocks are ugly). Conversely there may also be complaints about things that seem trivial but turn out to be important later on.
And sometimes it's important to measure what I call "the inverse bitch factor" -- things that generally work well don't generate complaints, and few people take the time to go online and write glowing reviews -- they're too busy shooting!