Obvious rule, the more something affects you, the more likely you will participate in a community about it.
It’s not surprising that communities about health do so well, nothing is more important to us. Likewise communities that touch upon the very essence of who we are usually succeed. These include communities of sexual orientation, locality, profession etc...
These are followed by communities about things we do for fun, our hobbies, or for those in a similar interest group.
However, the further away you move more from that immediate self-concept, the harder it becomes to create a community about the topic/issues. It's why most communities are doomed before they launched, the subject just isn't important enough to it's member to participate.
Also, most communities about products are doomed. Very few products are important enough to our self-concept. Motorbikes and iPhones perhaps, toothbrushes and furniture certainly not.
If your product isn’t that important, the only option you have is to build a broader community beyond just the product. Instead of toothbrushes you’re building a hygiene community. Instead of furniture you’re creating interior design and perfect home communities.