You need to decide for yourself what crosses the unacceptable content line and what does not. HN only provides the following guideline:
> On-Topic: Anything that good hackers would find interesting. That includes more than hacking and startups. If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity.
In fact, if that's the rationale I support it... though it would be good to know what the current rule of thumb is in order to play along.