Originally Posted by
threeoh
I don't think United or any other major U.S. airline is doing this, but I do agree it is technically feasible. They wouldn't have to manufacture a new fare or anything, they would just have to sell you one fare bucket up in price, like sell you a W fare even if the fare inventory is S2.
But, I don't think they do this.
In my experience, they have certainly done this in the past. One way to avoid it is to clear cache and cookies, as OP noted. But you can also easily test this by using different browsers (I currently use three).