The odor people are talking about has to do with the construction of the rug which is wool gunned through canvas then glued with latex. From my understanding, the buzz word on the street is that many of these Pottery Barn Rugs that have shown up on eBay are in fact, real Pottery Barn Rugs. How these sellers acquire the rugs is any one's guess, however the fact remains that much of the reason why these sellers have the rug probably has to do with this odor you are suggesting.
These particular Tufted rugs from Pottery Barn did have some problems from what I've understood. Although, under certain conditions, almost any hand tufted carpet will have problems to some extent. Heated floors, deteriorating glue and even just opening the rug for the first time will release this odor.
The odor people are talking about has never given me headaches as some other people claim, but it can be very strong. It smells something like hot rubber, or a little bit of an electric smell. Sometimes you can see deterioration of the tufted rug by slapping the rug against the ground to see if a white powder comes out the back, or folding it in one small area to hear for a crack. Both these things imply the rug is deteriorating.
http://rugrag.com/post/2...Hand-Tufted-Carpet.aspx
http://rugrag.com/post/Our-Rug-Smells!.aspx
http://rugrag.com/post/H...TuftedMachine-Made.aspx