I eat a lot of corn fed (supermarket) steak and I have, on occasion tasted the petroleum infused undertaste you are describing. Notwithstanding, I still find it pretty damn good. My experience with grass fed is minimal, however.
Recently I ate at two prominent national steakhouses: Ruth's Chris and Outback. Ruths Chris is about three times the expense of Outback and was worth the money. The steak at Outback was not good and slightly ovecooked. Also, my wife got a steak they called a "filet" but it was not filet mignon. She did not eat all of it, and I cleaned up the rest. I think she was served one of those glued together steaks, as demonstrated in this video: http://www.youtube.com/watch?v=4PE9rdmvIz0
Not very appetizing. Also, unlike the rubes in the video, I could tell it was a piece of glued together meat because of the inconsistent taste to the meat and the inconsistent muscle fibers - some ran north-south, some ran east-west and still others straight at me.
I dont appreciate paying for what I was told is a steak and being fed not-ground ground beef.
This practice just boggles my mind. We live in such a hyper-regulated society, I really didn't think it was legal. I mean -- why regulate the calibration of deli scales when you can just fictionalize the shit you heap on them?
On the beef topic, I've come to have a load of fun learning to prepare the cheap cuts and organ meats. It's almost a perverse game I play where I cook the cheapest stuff I can find. It's resulted in disaster a couple of times, and organ meat disaster is really a disaster, but mostly it's be a great surprise.