Expats in Clayton are the majority of people living there, so they are treated fine. There is a huge expat community in Clayton and the US embassy (pictured with US Marines in a joint exorcize training) is there so there are plenty of Americans and plenty of English speakers. There is no discrimination and nobody is treated poorly.
For the most part, Americans are treated well in Panama. The average Panamanian on the street is very, very friendly and very nice.