IMO the issue isn't finding those communities, it's having the pop up in your feeds. Which is why I think the ability to create multiple feeds is a feature we should have. Instead of having just "all" and "subscribed" we should be able to create our own groupings of communities. For example you create one feed called "memes" and then for that feed you subscribe to the meme communities and then you create movies/shows feed subscribe to the movie or TV show communities you care about.

In a similar vein you can create "communities I want to grow" feed where you collect all the low activity communities you'd partake in if they showed up in your feeds.