I have had these Design Spot 250 lights for about 9 years and the rubberized coating on the plastic covers of the lights had deteriorated into a sticky oily mess. You couldnt touch the units you'd end up with hands full of a greasy glop. No spray solvent I tried would remove this stuff. Elation couldn't help me, they wanted to sell me new replacement covers. They couldn't even tell me what the coating was made of. Each time I touched the lights I had to run and wash my hands. My workers didn't want to handle them; they complained "these lights are gross".
I finally figured...soap removes the substance from my hands. So as a test, I took off one of the panels and soaked it overnight in a container of hot water with lots of Dawn dishwashing liquid. This dissolved the old disgusting coating to the point where it could be wiped off with a rag. The plastic cover panel looks almost new now.
There are 15 panels that have to be removed from the fixture and cleaned this way. Take them all off and immerse them in a large tub. In 24 hours they can be wiped and rinsed clean. Use lots of Dawn. It takes about an hour to remove them all. A philips screwdriver does it but you have to be careful; if you are not technically inclined you can damage something.
I hope this helps others with the same problem.