A friend of mine a month or two ago mentioned that he has used the BA lounge at IAH when not on a BA itinerary (but on an otherwise qualifying itinerary), which is not the same treatment I've had at the SEA lounge where my CX Gold card won't get me in even if I'm ticketed on an AA marketed and operated flight that day. My friend's experience does seem to go against that of AlwaysAisle, but I do believe that BA lounges in the US do play fast and loose with the oneworld access rules.