There is a significant difference in the ownership of Fairfields and Courtyards and that difference contributes to the inconsistency seen at Fairfields.

Marriott has 3 or 4 "big owners" who own the majority of the non-Fairfield properties. These properties are franchised and managed by Marriott.

Fairfield properties, however, are owned by a bunch of "small-time" operators. For many Fairfield owners, it may be the only property of any franchise that they own. So when you have 500 Courtyards owned by the same guy (actually a company, but whatever), you'd expect a little more consistency in the product. When you've got 500 Fairfields owned by 400 different people, inconsistency is understandable.