End of post. Click on something else—preferably about cats—and never return to this or any other legal blog ever again.
Ok, but in all seriousness: the answer is of course more complicated than a simple "yes" or "no" because online advice, like all advice, is of varying quality, and because we go to online sources for many different reasons.
For instance, if what you're looking for is an answer to a very specific question, like "What forms do I need to fill out in order to start an LLC?" the Internet is a great place to find such discrete bits of information.
But if you're considering whether to sue someone and you want advice on what to do, the internet is going to be, at best, a useful starting point in a much larger project that will require consultation with other sources, attorneys likely among them.
With that in mind, here is some food for thought on getting the most out of online legal sources:
Information isn't the same as advice
Most online legal content, even if it's written by a lawyer, is generic by nature. Blog posts, articles, and "how-to's" are written at the 101-level and intended to introduce a topic—not to tell you, personally, how to handle a situation you are dealing with. Legal information that isn't tailored to your individual case or needs should not be confused with advice on how to proceed.
Some websites allow people to ask specific questions and real attorneys answer them, which is a shade better because the answer is matched to your particular question. However, contributors to these sites will usually draw a line between the "opinion" being offered and actual legal "advice" because attorneys want to limit their professional liability if you aren't an actual client.
Lawyer = expert?
The question most people will be asking when they read legal content online is, "Was this written by an actual lawyer?" It's true that a lot of blogs and websites that deal with legal topics are written by people who aren't lawyers (hint: you are reading one of them right now!) and it's never a bad idea to know who the information you are reading is coming from.
But even if the author is a lawyer, it doesn't mean you should take what they say as gospel. First of all, as noted above, good advice in general isn't the same as good advice for you. Second, lawyers have very different areas of expertise; just because someone passed the bar exam doesn't mean they are qualified to assist you with any legal matter. A paralegal who has worked on tons of cases related to the question you are researching probably knows a lot more than a lawyer who has little to no real-life experience dealing with cases relevant to your query.
Your case, your call
The question of whether you should trust online legal content hinges on that word: "trust."
The truth is that even in the "real world" unless you are a paying client the level of specificity with which an attorney will answer your questions may be no higher than what you'd find in a generic online post—because lawyers are hesitant to dispense legal advice to people who aren't yet clients.
But the process of building trust is not purely rational. Even if the information we are seeking could be found online, most people build trust more readily when dealing with another person than they do staring at a computer screen. This is because we believe—rightly or wrongly—that face-to-face communication helps us make sound judgements about someone's trustworthiness by picking up on subtle cues (body language, tone of voice, listening skills, etc.).
So the question of whether to trust legal content you find online is less about the inherent quality of web-based information and more about your personal preferences when dealing with legal matters—because whether you are clicking on a web page or walking through an office door, it will always come down to using your best judgement about how to get the most out of the resources at your disposal.
This blog isn't written by a lawyer. We write it because we hope people will find it useful. Should you trust what it says? You're a much better judge of that than we are.