For instance, for no good reason, stories I send to myself via the "share" button on a lot of sites have an overly descriptive "header" in them that basically reveals the entire content and tone and POV of the article. It's more descriptive than even the headline. I am not comfortable with this. so I take the time to change the header to something like "read later".
Once companies get keyed into the "public nature" of metadata, - if they aren't already - believe that they will generate the most revealing metadata they possibly can for whoever pays them to do so.
Metadata is often talked about as though it were all just naturally occurring phenomena , like the particular mineral content of water in your area and we're all standing around going "golly, look at what can be teased out of this here bit of nature " when in fact it's a human controlled creation which can be engineered just as humans see fit.