You should always search for a story before posting it (IMO). In fact i thought HN did this automatically but apparently not. I always search in case the same story has been posted from a different news outlet. Thats just good manners and avoids cluttering this place with dupes. Unless you're a karma whore...
No, you should just post whatever you find interesting and the site allows you to post. If it gets upvotes it means the community likes what you submitted. I'd say karma whoring is encouraged.
Why do you say it is terrible advice? The only thing I would add is the qualifier "intellectually" before "interesting". The other kinds of interest are not such a good fit here.
IMO karma is the worst aspect of HN. If you post any comments that are controversial or against the prevailing tech dogma you tend to get downvoted, whereas flashy press releasees about dubious original research get lots of upvotes (that obviously doesn't apply to this article).
