It almost smells like paint fumes have gotten on it but I always keep it stored in a scent safe plastic bag.
They don' t happen to be those from Hunter' s Specialties, are they?
I had this EXACT same problem. Kept my liner suit in HS plastic " scent free" bags. Thought I was doing everything right. Ended up with the same exact odor. I called Scent Lok, they couldn' t figure it out, recommended I wash them in hot water then dry on high for several cycles to " refresh" them. I did, and when I used atsko sports wash (walmart, $4), it finally got rid of the odor. But it kept reoccuring.
I just got my clothes to wash and get ready, they had been stored in a rubbermaid type container since last season, only I didn' t put my scent lok in the HS bags, even though they bags were also in the container. EVERY SINGLE PIECE of my hunting clothes had the same chemical smell. I grabbed the plastic bags, stuck my head inside and smelled them, they are definitely the source of the odor. All the smell washed right out, and the bags hit the trash can.
I didn' t notice the problem the first year I used these bags. Each and every year after, I did. I guess over time they break down and contaminate your clothes. HS probably designed them this way so you' d buy new ones every year...
Even if yours aren' t HS bags, chances are it' s a similar type of plastic used to be scent tight. Ditch the bags, wash your stuff in sports wash (carbon in hot, all other in cold), hand others out to dry, carbon in the dryer on high for a good 2-3 cycles, store all in a big rubbermaid type snap on lid tote and you should be back in business.