With decent algorithms, all user data is personal.
Where should companies draw the line in collecting
information about us in their efforts to sell things?
For example, should they catalog medical ailments or
physical attributes such as obesity? What about
religion, race, or sexual orientation?
Doesn't work. Writing codes of conduct for what's sensitive or secret information about a person, and what's not, is just a sacrifice of perfectly good carpal tunnels.
Once you turn the algorithms loose on a customer data set that's been carefully sanitized of anything medical, ethnic, or otherwise personal, they'll promptly reconstruct it.