First off you have to consider the sources. Many people do not have the knowledge or experience to give advice based on your situation, so they give it based on their experiences. If the person answering your question is still in their teens, their experiences will be very limited, quite often to one incident that may have occurred in their lives that may remotely resemble the problem you're presenting in your question.
Another reason could be bias. Some people already have a preconceived notion or opinion about certain issues. Their answers will reflect that when you read them. This isn't sound advice so much as it may be a praise, a rant or just plain ignorance.
Yet another reason could be trolling. These people seem to have too much idle time and aren't really able to, or have no desire to try and connect to a problem and think out a viable solution. They would much rather stir the pot and just make replies that clearly make no sense at all.
Of course then you have your point chasers. They may try to give you an answer that may give some insight to your problem or inquiry, but they don't wish to spend too much time giving you long and well thought out answers that would give you complete insight and understanding to your question.
Basically when you pose a question, since its out there for the entire site to see, you're going to draw a mixture of responses based on the type of people who happen to come across it. While some of thee answers you receive may be useful, its clear others won't factor into a solution at all. You can't control who decides to answer, so the best thing you can do is read all the answers and interpret them for face value. If an answer appears out of touch or off base, then ignore it. If an answer is thought out, seems to address some or all of your concerns and appears useful, then those will be the answers you follow in terms of formulating the best possible solution to your question.
Because it is the blind leading the blind!Haha :-P Also people need to know a person reasonably well to give good advice,right?If people in our real life can't give us good advice when we confide in them,how much less fellow GAGers could help us,right?But there are exceptions of course :)
Because most of us are just regular people; not advice columnists, not dating experts, not therapists... we're just the every man, so to speak. So the advice we give simply reflects what has or hasn't worked for us or the people we dated.
And the other reason - some people aren't here to help anyone. So they just put whatever in the answer box and collect their points and/or troll on purpose.
I haven't really received "bad" advice, not really. It's all a different option to consider.
You need to be expert in an specific area in order to give useful advice. People who give advise based on how they feel about the questions give crappy advice. For instance, I've seen a lot of useless dating advice coming from women.
I don't think I've gotten any bad advice, but the funniest was a 16 year old girl trying to give me sex tips. I've been having sex longer than she's been alive. I don't know that she's got any tricks up her sleeve that I haven't done.