EDIT: It has been bought to my attention that Scott Alexander makes a similar argument in https://slatestarcodex.com/2014/03/24/should-you-reverse-any-advice-you-hear/
I’m going to be very specific here because if I write platitudinously I might fall into a similar trap to the one I describe. The brief version of the argument though is just that we all take on board the worst advice for us- the advice that encourages us in the direction of the extreme aspects of our behaviour we’re out to justify. Here’s why
1. By non-specific advice I mean advice that:
A) Isn’t directed to a specific person.
B) Doesn’t give concrete information like “Don’t talk to cops without a lawyer” or “Don’t use Google to diagnose your own illness”.
2. By “effectively bad advice”, I mean that its effect, when people take it up, is generally bad.
3. This is only a conjecture because I present plausible considerations in favour of that conclusion, but without having catalogued a random sample of such advice, let alone performed experimental research on how it effects people, I don’t really know.
4. Consider generic advice:
A) “Self-care is important, don’t work too hard”
B) “Effort is the mother of fortune”
C) “Think through things carefully”
D) “Trust your instincts”
E) “Discretion is the better part of valour”
F) “Fortune favours the bold”
G) “Spare the rod, spoil the child”
5. In general, such advice can be seen as an injunction to move towards one or the other pole of an Aristotlean dyad. Usually, there exists a contradictory platitude that tells you to move towards the other one.
6. By an Aristotlean dyad I mean a pair of extremes, between which lies some virtue.
7. For example, a person can be stingy (not spending enough money) or prodigal (spending too much money). They can be lazy or a workaholic. They can be a cruel parent or an indulgent parent. They can think things through step by step, or they can rely on their intuitions. They can be cowardly, or foolhardy. In each case, there is some point somewhere in the middle which is optimal.
8. Most non-specific advice can be conceived of as a generalised exhortation to go towards one extreme or the other.
9. Now this is the crucial step. For any bit of advice, for whichever extreme it counsels moving towards, people already closer to that extreme will be more likely to agree with and feel affirmed by the advice. The indulgent parent will roll his eyes when he reads “Spare the road, spoil the child”, it is the strict, perhaps even abusive parent who will nod his head and go “That’s a really good point and agrees with my outlook, maybe I should be even tougher”. Of course, this isn’t necessarily true- maybe indulgent parents will be more influenced by “spare the rod, spoil the child” than strict parents- after all, they are starting from a lower base. However, my experience says maybe this isn’t right.
10. I know this isn’t a smackdown argument by any means, but it’s always the nasty person posting everyone’s a snake and you’ve got to have sharp elbows. It’s always the lazy person posting that it’s so very important to take time for yourself. I could go on, but you get the drift.
11. So I make the following conjecture. In general, platitudinous non-specific advice tends to get picked up by people who already favour whichever Aristotlean pole the advice counsels you to move towards. If it has an effect on them at all, it makes their behaviour more extreme and encourages them to avoid questioning their actions.
Slatestarcodex made similar argument: https://slatestarcodex.com/2014/03/24/should-you-reverse-any-advice-you-hear/
I think this is generally correct, but I've always considered "good" advice to be inherently context dependent, given that there are basically no "universals" among human behavior. So, because of that, advice is generally meant by the giver to nudge the recipient based on the perceived context towards one of those dyads). So the existence of contradictory maxims is a feature, since the "right" one can be deployed by the skilled advice giver to point the recipient in the correct direction.
This generally fails because both advice givers and recipients are terrible at correctly interpreting context (because most humans are bad at most things, compared to the "ideal"). So advice givers are generally giving the same "wisdom" to everyone, since they assume the recipient's internal context matches their own, and the external context they *want* would be for more people to move towards the extreme they think is "better." Similarly, if you're "looking for" advice, you will either search the internet, and find exactly what you want to hear, or ask multiple people, and remember the advice that most matches your priors (although you might also remember the most surprising advice as well).
Unless the advice giver actually has both the wisdom/experience to know the subject of the advice, and a well enough developed theory of mind to know what the recipient needs to hear, the advice will probably be neutral to bad. Of course, giving and receiving advice is probably more important for social cohesion and maintaining relations than any informational content which is exchanged, so the fact that most advice is "bad" doesn't actually matter for its existence.