Why blends exist
A blend is a decision. It should tell you the ratio.
A blend is not a way of hiding the cheaper bean. Used properly, it is a way of keeping two things you want: the aroma of one species and the body of the other.
The only useful number
“House blend” tells you nothing. A percentage does. Seventy percent Arabica and thirty percent Robusta is a specific cup: still aromatic, with enough Robusta that the coffee doesn’t disappear into milk or go thin in a press.
If a blend won’t say what it is, it isn’t being honest.
Single-origin storytelling is optional. The contents of the bag are not.