Recently I pulled out my X52 setup, which has been in storage for a number of years. To my great delight i discovered that the rubber bits had turned super sticky like someone had dipped them in syrup, and is caused by oils from hands. Thankfully all was not lost, though the fix takes some time. The solution I found was to use a lint free cloth and rubbing alcohol on it. You need to work on small sections at a time rubbing with a good amount of alcohol on your cloth. It should turn shiny fairly quickly showing the base plastic (the rubber is just spray on and very thin), then you just move on to another section till everything is shiny and sticky free.
The other solution is talcum powder, but I doubt it would last very long.
Honestly I wish Saitek had skipped the rubber spray on garbage to begin with.