i had the GXP for a very short time in stock lighting, but when i got the car both fog lights were fine, and i installed HIDs and they are flawless for 2 years now.
they say "The GXP was more of a hit and miss" but i dont believe that, i think it all depends on how the pervious own took care of it, when i bought mine it was a lease return by some guy in a city close to mine, the back seat was never sat in, and the front was flawless with less than 25k miles on it. i take care of it really good, and so far its amazing
I also think a big part of the issue is when they go into service for minor things, most GM service men dont know how to take a GXP apart and put it back together, many times GM itself will ruin your car, this just happened to me this month, 6 times into GM in one month because of something they screwed up
as for the smoke, why dont you ask the current owner about it or ask them to check it and let you know since you're serious about the car
2005 Phantom GXP - Stockish