If you came across this guy on your street, sporting a big watch and a huge wad of money, would you ask to use his services? Not likely, most of us would cross the street and walk quickly in the other direction. In this case however, he is one of the many money changers found on the streets of Granada.
Most of them are located around Central Park or over one street around the banks. In fact some of them actually work for the banks. Now I know many still will not trust them and that's OK, banks and ATM's are plentiful. However these guys offer the current rate (easy to check before you go), no fees and no line ups. Of course be wise, don't flash huge amounts of money around, watch him count out the money and you re-count it before handing over your cash. Always ask what rate he is giving, if it's not agreeable to you, simply move on. We have always found them to be polite and not pushy.
Just a little word about money here. When you get your US cash to bring ask for clean bills. That means no rips or marks of any kind. I thought the travel books were exaggerating this point but no they were not. We have a $20.00 US bill with the number 20 written in pen on it. It has been refused everywhere!! Not sure the reason for this, but it is not urban legend, it is true.