This is a good question! I've never really put much direct thought into it, but I know I make decisions on what to share with this stuff all the time.
It comes down to what the brand/community is, who will see it, and how much I'll have to explain. I'm far too old now to be embarrassed by anything I enjoy, but I don't always want to have to get deep into the stuff. A bit sad, but perception in a professional environment means quite a lot, so you can't always be super open even with mundane stuff because it may be seen as childish.
I think I don't need or expect any kind of recognition from the brands or communities I participate in. I'm picking stuff I like to do and doing it. My supporting these things helps keep them going and keeping me entertained. I make it sound extremely transactional, but that's just how I see this I suppose.
I am an older guy who crochets and that's not the most common thing. It is my favorite hobby and I openly share that with anyone and everyone. I want to expand the group of people who crochet and use yarn. It benefits everyone when a community like this gets larger. It's also the most welcoming community both in person and online I've ever been in. The fiber art community as a whole is generally pretty awesome.
I moderate two channels on Twitch and I keep that pretty quiet. It's such a difficult thing to explain to anyone who doesn't know what Twitch is and/or isn't really into video games. I'll share that I watch Twitch to see what new games are out and how they play. I think there is a fairly good social aspect with it as well that I'll share. I've made a few very good friends from it and even got to hang out with one when we went to the UK for vacation.
The Australian YouTube channel Mighty Car Mods is something I'm a big fan of and support. They are very funny, do cool things with cars, and support their local community in good ways. I've got a few of their T-shirts and a couple of hoodies over the last couple of years. It's an interesting community in my part of the US because they aren't that well known, but when you find someone who recognizes the shirt, they are pretty good to talk with.
On a more 'good product for the consumer' level of support, I cannot speak more highly of Kawasaki Motorcycles. I spent six years and 23,000 miles wildly abusing my Kawasaki Ninja with no issues. This summer I bought another one and it's been just as awesome. I don't run around in any of their shirts, but if someone asks me about my motorcycle or is considering getting one, I'll share my experience.
I've enjoyed being fairly early to Just About. It's nice because everyone from staff to members wants this to work out and be a good place to be.