Star ratings in restaurant reviews
My day job requires assigning star ratings (not of restaurants; I don't write about food anymore), and every place I've ever worked, the star-assignment system has been fairly arbitrary.
We actually wouldn't do them at all at my current workplace, except that our syndicate made us add them because they think The People want star ratings.
Most pros hate them. They'd be fine if they came with a giant disclaimer: "This rating is relative to other restaurants of this type, not part of some one-size-fits-all scale." It also makes it easy for readers to just look at the stars and skip reading the actual review. I'm grateful I don't have to use them.