In its general form, as everybody here has pointed out, the question is ill-posed. Truly "plain wrong" general advice doesn't exist because you can always find a percentage of startups for which that advice worked. Most advice that's not outright nonsense ("give all the money you are going to invest in the startup to homeless people and wait for the Universe to give it back to you 10x") will work within some reasonable necessary/sufficient conditions with a certain probability.

The vastly more interesting question is: for a specific startup in a specific situation, is there advice that's just plain wrong? Is there advice that is "plain wrong for Quora for instance? Very apropos, since a lot of people are giving Quora advice right now (myself included: Venkatesh Rao's answer to Has Quora lost its way? )

Not quite, but there is advice that is systematically flawed. People who give this advice without adding self-correcting caveats are either rationalizing these actions as "in the best interests of the startup" or being consciously malicious to a degree.

Basically any advice that you get from anyone whose risk exposure in the project is different from yours is likely to be systematically flawed for you, unless the person giving the advice is a highly self-aware saint.

In the following, I'll assume you are the main hustler in the operation.

Examples:

1. VCs who have an interest in big exits and are motivated to steer you away from modest ones are going to give you advice that optimizes for their exposure profile (big exits). I'll be politically incorrect here and state my view that lean startup models in their out-of-the-box form actually optimize for investors, not entrepreneurs. You need to "jailbreak" the model in order to make it work in your (entrepreneur's) interests.
2. Advice from the more technical team members is going to be systematically flawed towards greater technical and business risk. Technical team members can walk away from a crash-and-burn with their reputations intact or even enhanced if they manage to put the blame on the hustler/business types and claim credit for some technical breakthroughs. It is in their interest to hedge against failure by encouraging investment in things that enhance their personal technical resume.
3. Advice from consultants who provide "deliverables" is going to be systematically flawed by focusing far more on process than is necessary, because advice in that form lends itself to packaging in "deliverable" forms. If I promise to deliver to you a Master Marketing Plan in a beautiful PowerPoint and spreadsheet, I'll naturally manufacture advice that makes for better PowerPoint and spreadsheets.
4. Advice from consultants who claim to offer "performance based services" compensation and use rhetoric like "we don't get paid until we actually improve your numbers!" is going to be systematically flawed in terms of prioritizing short-term performance metric gains that will vanish once they collect their "performance linked" compensation and disappear. This is basic pump-and-dump consulting.
5. People who bill by the hour are likely to offer advice that creates billable make-work for themselves. Since this is my own main consulting model, I personally know how temptation stares you in the face. It is just so damn easy to spend more time doing bullshit if you can simply bill it. You'll have to take my word for it that I am pretty scrupulously honest in my billing, and if in doubt, I generally don't bill it.
6. People who have books to sell and rehearsed talks to pitch are going to be systematically biased towards quick inspiration hits. "You really need to get the team pumped up and forged together around a common set of ideas." (i.e., "let me pump 'em up for you and offer you some viral, sticky ideas to bond over, that you'll likely repeat, resulting in free PR for me"). A good rule of thumb for advice associated with a book is that the most successful advice isn't the advice that creates startup success. It is advice that spreads the most easily. Basic principle of memetics.
7. People whose interests are primarily intellectual/researchy are going to give you advice that promotes their own learning over your success. They are going to tell you to do (for instance) more analytics and experimentation than you should because they'll get to share in the mined insights and package it up for sale to others, while you're left holding the bill for their R&D investments.
8. People with some sort of ideology to sell are going to encourage you to do things that validate that ideology or help refine it in the case of "controlled failures" that can count as learning for them.
9. Finally your OWN advice to yourself is going to be systematically flawed because you're going to give yourself advice that is easiest for you to follow. You'll use ideas like "play to your strengths" as justification. And yes, there's a principal-agent problem and moral hazard here. The VCs are much better at it, but you are definitely going to at least subconsciously be more careless with their money. If you doubt that, just ask yourself: if it were your own savings rather than the VC's money (okay, the money from little old ladies' pension funds forked over by LPs to VCs, each with their own layer of rigging things in their favor) would you act the same way?

The point is, all advice is systematically flawed and you can predict exactly how by asking the simple question: what actions by my startup will maximally reward this person, for minimal risk? Including yourself. Yes.

Heck, even this advice that I am writing now is systematically flawed because it favors what can be written down, and since I like writing, I am more likely to give advice that can be transmitted in written form.

Can you systematically counteract this tendency? Yes.

It takes continuous self-awareness, a willingness to admit that people aren't pure as driven snow and that most people bring to the table either a conscious or subconscious intent to manipulate the situation to their advantage. The unconscious ones are the worst because they'll delude themselves into believing that they are genuinely acting in good faith, in the best interests of the advicee.

Full disclosure here: I've consulted by the hour, by the project and by the speaking gig. I do my best to be as mindful as possible of my own, and others' motivations (at both acknolwedged and conscious and unacknowledged/subconscious levels). I try to cancel everybody out of the picture and imagine what the startup itself intrinsically "wants" to do in some philosophical sense.


So is there a ray of hope in this bleak picture? Yes. The word mindful.
Any advice that is not mindful (in the sense of mindfulness meditation) is somewhere between systematically flawed and plain wrong.