This is now a common issue. I myself have been hit with 7 of these foul things. This is not user error, and there is nothing you can do to rectify it. If you head to the Technical Issues section of the forum, you will find an extensive thread about this. This is basically what was determined by Sun Vaporer
"I bought ten 510 atomizers (I am not going to name the vendorsand it is not their fault anyway in my opinion, rather it is a manufacture issue). Of these ten, four of them emitted a foul taste as has been reported with so many 510 users. I used straight PG and cut VG to rule out e-liquid and drip smoked to rule out melting polyester batting right out of the box. (I have not used cartridges of any kind and only drip smoke for over a year now anyway).
Using stock 510 batteries, these four atomizers gave off a nasty burnt taste. After disassembly of two of the atomizers, I can preliminarily conclude that the nickel mesh bridge wicking is inferior and is burning instead of just heating.
There are only three components in an atomizer that could be subject to burn: (1) the coil; (2) the fiberglass wick that the coil surrounds; and (3) the nickel mesh bridge.
Upon disassembly of two of the four atomizers, I found the coils to be in tack and the fiberglass wick to have no discoloration. I removed the mesh, as I have done on so many other atomizers to find that the nickel mesh had a tinged blue and grey color and a slight burnt smell that also crumpled in upon manipulation. The mesh in most atomizers has no smell or discoloration and does not fall apart or crumple like this mesh.
With another of the four atomizers, I removed the nickel mesh bridge and drip smoked the atomizer with the coil in tact only to still have this foul taste. The taste would not dissipate even with removal of the visible wicking bridge. I can conclude that this removal of the bridge did not work simply because the metal wicking also goes under and around the visible part of the coil and can only be removed when the entire atomizer is disassembled.
I then disassembled one of the atomizers that did not emit any foul taste of the ten that I purchased only to find that there was no discoloration, smell, or crumpling of the nickel metal wicking material.
Bottom line---- four of the ten 510 atomizers that I purchased, employ an inferior mesh wicking bridge that burns and emits a foul taste, and that no cleaning of any kind can be done to abrogate the problem. This issue has absolutely nothing to do with user error as this metal wicking bridge is not suppose to burn or emit such a taste and needs to be rectified at the manufactures level.
As a Consumer, I can not say how wide spread the issue is, but I can say that I get reports of it every day.
Sun"
I don't know! 
You can hear a sizzling sound and the LED light starts flashing. If you can unscrew the battery fast enough you're fine, if not you get that horrible chemically taste. I've got two atomisers lined up for a bath because of this.
