Originally Posted by
MSPeconomist
In many countries, it may not be strictly legal to give foreign currency to the locals, so I would be careful in the absence of detailed information about current laws. It could be interpreted as an offer to change money on the black market, for example.
Extremely extremely extremely highly unlikely in Argentina if you slip your concierge a US$5, 10, or 20 for providing excellent service. I also wonder if all the people in the airport lounge @ LIM will be rounded up for criminal charges for stuffing the tip jar in whatever currency they may have in their pockets, as I usually see quite a few currencies through the glass.
The real problem with smaller US bills is they aren't worth as much for exchange. A crisp new US$100 gets you "top pesos." A soggy old $5, not so much.
Nonetheless, if you have detailed literature regarding current laws in Argentina regarding giving your service provider a gratuity in a foreign currency we'd be grateful and love the education.