I was speaking with a general manager yesterday and he told about one of the big changes from a property's standpoint post-August.

He was saying legacy Starwood employed staff to conduct unannounced inspections/audits to ensure compliance with SPG, but legacy Marriott didn't. Now, Marriott will have mystery guests -- he didn't know how many people -- traveling to stay at properties and check their compliance in delivering the amenities and services required by the standards of the new, unified Marriott–Ritz-Carlton–SPG program. He was very specific that this would be focused on the loyalty component, not the actual physical brand standards of a hotel.

I imagine it will be a relatively small staff, but hopefully it will discourage bad practices by franchisees.