I'm working on an RSS feed reader, and it has a feature that solves that problem. For every subscribed feed, it shows the percentage of items that you actually bookmark and read. So if there are feeds that you subscribed to but don't read, you can easily find out which they are and unsubscribe from them.
It's called https://lighthouseapp.io
I've worked on this issue a little in a different context, where you can follow posts from people on Bluesky related to specific topics, and this is ideally what I would like to be able to do more of with RSS.[1]
It's a great point, and helps me extend the feature and make Lighthouse better. So, thank you!
Lighthouse actually has that data. It supports rules, and tracks if a rule made an action (e.g. archive an article). So basically the ratio could ignore all articles that were automatically archived by rules.
I need to think more about how the UX of it should be, but it's a good next step for the feature.