The last time I was in a McD (this year), it smelled faintly of feces, and yep it was a mess. It really did put me off going to any other McDonald's. I know that's one experience but prior ones had been trending in that direction.
The problem is they’re in an uncanny valley. They’re too expensive for low income customers and their food is too shitty to compete with other things you can get for the same price. Starbucks will give you food that’s similarly priced and much tastier and healthier. McD is disgusting.