Quote from condorll:
Perhaps the American tourists are trying to be polite by trying to speak Spanish?
If they spoke English without trying to speak Spanish they would be considered arrogant.
Damned if you do, Damned if you don't.
My experience after several trips to Spain , is that generally , if you learn at least to say, gracias, por favor, buenos dias etc, Spaniard appreciate your effort, even if your pronunciation or grammar are not perfect.
Obviously like any other place in the world , where the concentration of tourists is very high and locals have to deal with hundreds and hundreds of them everyday, courtesy might become an extra.(por desgracia)