First, Lang’s Law of Feeding Cats: if your cat is really really hungry, she will eat whatever canned or dry food you put in front of her. This has (for me) proven to be the most effective way of dealing with a “ﬁnicky” cat. Hunger overrides ﬁnickiness every time. (It’s true for finicky humans, also.)
Some cats, of course, are not ﬁnicky at all (lucky owners!), while some are extremely fussy, leading their owners to try one brand of cat food after another, usually buying on the assumption that the more expensive brand is more likely to please the cat. This isn’t necessarily true, but manufacturers have made a killing from the idea that cats are ﬁnicky, as evident in the success of Morris and the glossiness of the Fancy Feast food ads.