We had a meeting about privacy at work and the presenter told a story about his ISP who messed up his name when he signed up something like Roge rJones instead of Roger Jones. The ISP stated they do not sell customer information to 3rd parties.

Within a week after signing up he was getting spam and junk mail addressed to Mr. Roge rJones just copied and pasted right from the ISP customer database.

Indirectly in a way what you say to try, a unique identifier.