> they can adjust their algorithms to trust other people's data about you (if they're not already doing that), which would significantly decrease the effectiven

> they can adjust their algorithms to trust other people's data about you (if they're not already doing that), which would significantly decrease the effectiveness of feeding them noise about yourself. Maybe some people can inject noise about their friends, instead. For instance: 1. install the FB app on a phone with an address-book full of garbage and share it with the app, 2. inject fake geotag data in the photos you tag your friends in, 3. put the actual tag on strangers in the background, 4. tag your friends in stock photos, etc. Some of these you obviously can't do with friends who don't consent, since they may get annoyed by all the fake tags, but others would be transparent to most social media users.