I don't think that they would see a religion revolving around gluttony. Advertising is not similar to evangelism (evangelism has an implied element of teaching) and uniformity doesn't point towards a religion. There's also a lack of large and frequent gatherings, religious texts, nor grand structures, which are hallmarks of a religion. A religion is much more complex than what you'd see at a fast food restaurant. I think what an outside observer would think would depend on the range of their sight, so to speak. But either way, I don't think they could make many conclusions about our race as a whole. I think they'd recognize that we all have a sense of identity because of how different we all are. They'd realize that we are sentient life forms, and that that's all they could figure out with a quick glance observation. Assuming we were meeting an intelligent observer.