Rolls Royce is associated with a luxury brand of automobiles. If Rolls Royce restaurants, Rolls Royce pants, and Rolls Royce candy are allowed, then consumers will no longer exclusively associate Rolls Royce with a luxury brand of automobiles, even though there is no confusion about the source of the goods.

This is known as what type of trademark issue?

Fair use.

Blurring:

Tarnishment.

Parody.