I thought I was gonna pass out from so much misinformation in a single thread. Please refrain from answering questions if you're unsure of the answers. You do a disservice to the person asking the question as well as the animals.
First, Condylactus anemones are relatively hardy compared to SOME of the clownfish host anemones, but you can't "put em' in crap-water, predators, smoosh them with rocks, and even leave them out of the water for a couple of days." If you do any of the above, they will die! They are comparable to bubble-tip anemones (Entacmaea quadricolor) in terms of hardiness; perhaps even less hardy. They require reef-quality water and BRIGHT light to survive.
They are NOT active movers when kept under proper conditions. This includes the right food, water conditions and light. Again, they are comparable in this regard to the bubble-tip anemones, and much less active than many other anemones, such as Heteractis magnifica.
Continuing... Most clownfish will not host in Condylactus anemones, but a few will, such as Clarki's and Maroon's. Other species sometimes adapt to them as well.
Condylactus anemones can certainly "sting" corals but are far less potent than many of the Pacific Ocean host-anemones in this regard, especially the carpet anemones, which are notorious fish-eaters.
Condylactus anemones do not occur in polluted waters. In fact, I used to dive a pristine site in the Cayman Islands that was carpeted with beautiful Condylactus anemones. When I returned to this site a few years later, it had been affected by local run-off and algae had overtaken much of the area. 90% of the Condylactus anemones had disappeared.
Finally, Condylactus anemones will NOT "spread like the plague." As far as I know, they do not reproduce by fission, as do the bubble-tip anemones, aiptasia anemones and majano anemones. And they don't get as large as most of the Pacific host anemones. I have a purple Condylactus anemone in a 58 gallon reef aquarium for the past year. While it has gotten larger, it has NEVER moved and NEVER "spread."
In conclusion, the purple and pink varieties of Condylactus anemones make spectacular additions to a reef aquarium, as long as you understand their needs. Most of the specimens seen for sale in local stores are near death and look horrible. Once they recover though, they look great in an aquarium. Although they normally don't host clownfish, there are a lot of inveterbrates that use this species as a host, including some shrimp and crabs. These are equally fascinating relationships to obeserve.
Greg