Provided you clean you Fleshlight right away, the smell is probably the mineral oil material (75%) if you leave to caps on after cleaning this can cause the mineral oil smell to intensify - never store with caps on and always keep the sleeve in the case. If you are not sure how to care for a Fleshlight checkout http://sextoys4men.org/fleshlight-use-care/ - this site has lots of Fleshlight information.
The best thing you can do is to simply try and clean it (very warm water only) and then pat dry. Put the sleeve back in the case without the caps and then allow to dry overnight. Once dry, try a little sprinkle of corn startch.
If all that fails, your Fleshlight is probably beyond repair and time to order a new one. If so, make sure you follow the guide noted above.