This is just my opinion on how to identify bad advice. This itself may be bad advice. But I am compelled to write it regardless.
Beware of the forum.
A forum can be good. But it is a hard place when it comes to figuring out if advice is bad. So much bad advice is presented as a way for you to avoid making mistakes. The old “you’ll look like an amateur” statement normally follows this advice. Or that is only used in a production draft. I am not saying that these people are intentionally being bad advice givers. They probably believe it. They may even quote some book on rules. But if it seems too arbitrary it is.
The advice to ignore without question is the “you can do it when you are famous or it is dangerous to copy a successful writer”. Here is another article that covers that.
Bad advice givers.
Staying with forums for a moment, as they are a common place to get advice. Look at the person giving the advice. Check out their profile. So many people are trolls. See if they are good advice givers or just bullies pretending to give advice. These people usually attack other advice givers that have a differing opinion. They are desperate to hold onto all credibility. They see a different opinion as a reason to belittle or ridicule others.
While checking their profile is it possible to verify anything on their profile? They will claim to be a “script doctor” (not a real thing) or a “Consultant”. They may even say they are a produced writer or WGA member. Are there links to an IMDB page or a film you can Google? Does “SCRIPT-HERO-99” really exist anywhere other than that forum (sorry to anyone called SCRIPT-HERO-99, I made that name up)?
Most people with real credibility use real names.
Do they use it themselves?
That is the next question you can ask yourself or even the advice giver. How is that working for you?
I saw a question from a student that said they had been given advice by their professor and they would like advice on how to implement it. So many people jumped in with “He is wrong, don’t do it”. If it was a credibility war between a University Professor teaching writing and SCRIPT-HERO-99, I’d have to side with the professor. Okay universities can be teaching older forms of things, no matter the subject. But they also have resources and access to things we don’t. Their graduates are the industry greats that we aspire to be.
Advice that feels a little off is normally wrong. I would check it against several sources. I would run from consultants, gurus and doctors. Talk to writers. Read scripts, good ones first, then bad ones. Reading a bad script and seeing that it is bad is confirmation that you are learning.
If you get advice that makes you question its quality ask, “Who are you? Can I check your credentials to give that advice?”.
If they are not happy to identify themselves, ignore them. The “I was an executive, or I am a professional writer” is normally bullshit used to cloud the truth. They are no better than you. Their ego needs propping up and they are using advice to do it.
I know this article would have been some much better if I could have told you how to identify good advice. But that is the trick. Good advice and bad advice can look similar. Being able to spot bad advice, I hope keeps you safe. You’ll have to trial the other advice to see if it is good for you.