“Avoiding visas and anti-U.S. sentiment isn’t the only reason a second passport comes in handy. Privacy is a huge bonus. I regularly visit countries that don’t penalize U.S. visitors using my second passport. I do this specifically to avoid having entry and exit stamps in my U.S. passport, where TSA snoops can see and record them. My international travels are all for perfectly legitimate reasons. But so were those of Laura Poitras, a U.S. journalist and filmmaker who has been subjected to detention, confiscation of her personal effects, and other forms of harassment at the U.S. border — all because she is openly critical of the U.S. government’s abuse of our constitutional rights.”
http://thesovereigninvestor.com/asset-protection/advantages-of-a-second-passport/