I didn't see any specific policy, doing a quick search on the Sheraton site, but I've only seen these at less cosmopolitan locales, e.g. resort/beach properties where the policy is clearly stated. I've read in that in the past that the no shoes, no service rule was for aesthetic purposes in that businesses wanted to maintain a respectable appearance and by denying service to those who didn't have shoes, or couldn't afford them way way back when, that they achieved that end. But to-day with the legal concerns of guests with bare-feet possibly cutting themselves with broken glass or slipping because bare-feet have less traction that shoes, sadly I suspect the aesthetic concern would only be a secondary factor in establishing the policy. That's not to say I don't agree with the policy because I certainly do support it. Thankfully, I've not yet seen this, at least not that I can recall, in SPG properties. More often than not, I'm the one who feels under-dressed in jeans, t-shirt and tennis shoes.