I enjoy reading HNQ posts on my sidebar, but now and then, I spot questionable content I'd like to see removed. How do I go about that most efficiently?
Moderators can remove posts from the HNQ
It's a two-click process, easy as pie. So flag the post "in need of moderator intervention" and explain what you find problematic about its being featured.
Personally, if I were doing this on a site where I weren't a regular contributor I'd also drop into that site's main chatroom and ping a local mod to say "hey $localmod: I'm around in case you have any questions about that flag I just raised." It's not necessary, and I know people have mixed feelings about chat, but I think it's a nice courtesy.