Yea its a regular thing with that plastic on the handles AND it also infects the plastic trays in the toolbox. It don't ever go away. You just gotta clean them every so often (maybe 2-3 times a year?).
Couple things you can do...
-Clean the plastic handle tools, dry them in the oven on "warm" not "well done", then get a snap close sack to put them in. Then they'll only stink after a while and only when you open them.
-Use a toolbox with either metal trays and hardware, or the newer "tupperware" kind of plastic...but that develops its own kind of a stink too after a while.
-Clean out the "black fuzz" that gathers in everyone's toolboxes in the corners, and wipe the whole box down with alcohol.
-Sell the plastic handled tools and use wooden or fiberglass handled tools.
-Don't leave your toolboox open or out in the rain while you work. (Don't say you never do it either!)
-Don't use your screwdrivers to scrape grease (try a wooden-handled putty knife), and don't use solvents or cleaners that contain harsh petroleum ingredients on the plastic handles because this makes them start to "rot". I use alcohol or silicone electronic parts cleaner.
-Don't use your car tools to pick out belly button lint, or to scrape and clean other body openings. Don't use your car tools to cut your toenails, and if you do, be sure to throw out the cuttings from your toolbox. Better yet, use a toenail clipper. Plus if you check on eBay under "Medical Supplies", there is a whole lot of interesting special purpose stainless steel or surgical steel medical picks, cutters, and tools that you will have much more fun and success with on your body parts -- see guys its OK to use tools on your body...just use the ones that are made for it, and do it in the BATHROOM! (For those of you that are married your wives will thank you for not being gross with your tools.)
-Don't forget you gotta clean your tools and box more than once every two years.