Nancy, I have spd's and they did not get jammed up or anything from the sand. i wear SIDI MTB shoes, so they are really pretty nice to walk in.
At the end of the sand I sat down and shook the sand out of my shoes. I also wiped down my wheels where the brakes drag because i did go through one muddy place (from the water they were giving us)

i did see some cleat covers IN THE SAND.. i guess they don't stay on that good.