[recuter]

Have to start your search somewhere. Watch out for an older distinguished-looking gentleman giving proper tours, not the fellows that accost you at the exit of the bus/train station with a few simple sentences.

If I was a researcher with no travel budget I'd try cross referencing a list of medium-small touristy towns (like Cusco) with decades that had upticks in tourism and a very bad local economy. Narrow it down to above-average income college grads and start asking them if they are or know of a polyglot. Can probably get pretty far with nothing but Facebook.

Just a guess, maybe I'm wrong about this pattern. Let me know what you find out. ;)

Edit: I was also intrigued by your comment until I read "in the same way older immigrants have broken language" - this is indeed the common but rather narrow experience. I don't think I'll be able to convince you of anything. Best assume you are corresponding with the Loch ness monster.

[bynormous]

My work requires me to travel with guides, I have no idea if they are all above average income 'gentlemens' as you say (before you edited it out) so I can't really comment on that. I'm an immigrant myself along with my community so there's that. If you consider that a 'narrow' view not sure what more to say. There's a difference between fluency and native-like fluency that kids obtain. I would love you to post recordings of you speaking and ask the public to see if they can tell if you're a native speaker or not because I genuinely am curious.