I guess I have always been super lucky. I have never had clowns that didn't host their anemone.
But, hosting isn't all it's cracked up to be. Once the clowns deem the home theirs, they feed it. Anything they can pick up becomes something to feed to their nem. This included, hermit crabs, other fish, your favorite star fish, etc.
They also turn into the pit bulls of the aquarium. Because you are constantly preforming rescues pulling things out of the nem, you are also getting bit, which even if they don't get you good, I still jerk and get burnt on the lights.
It is rather fun to turn a powerhead or two and create the tsunami and blast the clowns right out of their happy home.