Locals of any particular location can spot a foreigner a mile away. In fact in many places, especially if you haven't got a well-researched itinerary, you may as well have a neon sign above your head that says "tourist".
While this isn't always a bad thing, it does make you an easy target for many scams that those with nefarious intentions know won't work on locals You can't really do much about this, but what you can do is arm yourself with strategies to both spot, and avoid, common tourist scams, so you hopefully don't fall victim to them.