Compared to Facebook (that could improve this too) Twitter has little context: according to most client, either you enjoy going through everything someone posts or you don’t see any of their contribution coming your way; this is great with dedicated individuals or with friends close enough to make their inner questioning, restaurant reviews and issues with insurance claims relevant — but most of the time, I have to chose between having no more wide-eyed news from the Silicon Valley or going through @loic’s “Should I run or sort my desk?” moments. Of course it’s easy to over-look those — but I’d rather have a computer do it, rather then me. Loïc himself had to go through that, and decided an energetic cleaning. Hashtags and search are trying to resolve that, but mostly are good for events or breaking news — and don’t even let you opt out of an event, at least not intuitively: you can always ‘mute’ someone, but you wouldn’t know when they are back to their usual meanderings. I can’t prevent @chrismessina from sharing his interests for great bargains (I don’t live in the US, so I can’t use any of these), but I need his insights on the OpenStack.
Twitter can’t really give a pre-set list of contexts, because to some, family is work, or work is their passion; to some, music is their job, or their job is to find restaurants. However, people seem to be quite good at setting up a list of contexts that they step in: hashtags have been meant for that, and the aforementioned twitters and many others have rightfully added a #deals or a #weightloss to their blurbs. What I haven’t seen is a client able to take those away. It would then be up to followers to enforce a clear and systematic code from those seeking attention. This could be done either at the general level, or by followee; although with poster-specific hash-tags, these might not be very different.
Why negative filtering only? Because it would help greatly to balance the two positive way to get content: subscription and keyword search, and be symetric to the negative “-user:johndoe” option in search.