I have no idea about the technical ramifications, but a few years ago, I was flying in to BOS to give a talk. I was using my British passport under vWP.

At initial screening, the CBP officer said that I had "visited the US too often" and asked why -- I said that it was mostly because I was an academic, but also have friends/family here. Anyway, I was asked to go for more detailed screening...

Some long wait later, I go up to be interviewed, the guy asks me why I'm here, I say I'm giving a talk at a university. He asks what my field is, I reply, then he starts quoting one of my academic papers at me! I was in total shock, thinking the CIA or whatever had a file on me. After a brief pause, I asked him how he found that out. One word response: "google".

To be honest, if I was a determined threat, I would have prepared a thorough back story anyway, including google-accessible data, but to the casual liar/ illegal, it may be of some limited value.

tb