I have one of those fermenters too, and the few times I used it I didn't have any taste/odor issues. I believe the fermenter body is made of low density polyethylene (LDPE), and the cap is plasticized PVC. That being so, then there are no plasticizers in the LDPE, though there are some stabilizers in it. But they should be food grade, not extractable, and if they are, then they shouldn't affect flavor or odor. A good soak with hot water and PBW or Oxiclean as others suggested should eliminate any problem you may have with taste or smells.
The cap being plasticized PVC does have plasticizers in it, and they could be contributing to your problem, but again they should be food grade and not contributing to taste or odor. The plasticizers are probably the same as used in the vinyl tubing many of us use to transfer beer and hot wort, without problem. Since the fermenting beer isn't in contact with the cap, the chance for leaching is pretty slim.
I'd be quick to email or call the manufacturer. I had a problem with mine that I bought used, and emailed the company and they were very helpful in solving my problem, even though I hadn't bought it from them.