I look at HN discussions. I deliberately look for technical subjects where people, in apparent popularity, claim cannot be solved or will not work versus the practical application for users in a business sense.

In the broadest of terms this frequently boils down to boring technology solutions to common business problems people are afraid to solve out of inconvenience. More specifically, recent subjects have included anything about privacy, IPv6, security, and just about anything disruptive to online advertising.

Edit:

I go out of my way to do the opposite where discussions popularly advocate for something with false expertise or clearly based upon a faulty premise. Examples of these subjects are security in software development, anything related to mental health, law enforcement, and so forth. All the garbage that seems popular online but is antithetical to real life practice from paid professionals.