mk is much more authoritative than I, because as many #bugski posts as I've made I've never bothered actually reading the hubski code, but as far as I know if a post is in your feed it is because
1) you follow the poster
2) you follow someone who shared the post
3) you follow one of the tags on the post
In general, following people who post/share things you're interested in is better than following tags, because we're only consistent with a handful of tags around here and hubski is low-traffic enough that the posts you don't care about you get from following people aren't going to drown out the posts you are interested in.