I have a trick that has kept all my rubber bodies perfect for years, just like they were brand new.
Alot of collectors don't like them but if you manage to do something twice a year, it will go a LONG way to protect them.
Yes, strip it and wash it, do whatever you want to get rid of the stain.
The most important thing is to rehydrate it so... you put scentless hand cream on it, smear it around until you can feel it start to obsorb it... after that, just leave it for 10 minutues. The rubber actually will be moisturized and ready again for clothing.... you will see no evidence of anything you did. You can even oil it a bit after with a bit of cooking oil (only for hellboy and fabio if you have a HT fabio)
The only warning I have or don't do is, after this process, wait a bit before folding the elbow joint so much that the bicep touches the forearm, it will stick, and if you leave it for months and months, it may bond or discolour.... so wait a few weeks before you pose it with skin on skin... (whether you use hand cream or not, long term skin touching is bad anyways)
Ok that is a secret for sure... might have posted it before but I hope you all appreciate it.