The Coral Springs place use to be all red clay. The public complained it stained their socks and shoes so they took out all but one of them.
There are 2 red clay courts at Lakewood Ranch Tennis Center outside of Sarasota. When we lived there we could play on them anytime we wanted. Everyone else played on the Har Trus, same deal, they said they stained their footwear too much!
Very true about the Har Trus. Most of them are very thin coatings and dry. They don't play anything like red clay.