The latter would be apt to fill his work with irregular patches, sometimes taken verbally from the writings of the author whom he personated, but rarely acquiring his spirit.
His imitation would be obvious, irregular, superficial.

The patches of purple would be easily detected among his threadbare and tattered garments.

He would rarely take the pains to put the same thought into other words.

There were many forgeries in English literature which attained a considerable degree of success 50 or 100 years ago; but it is doubtful whether attempts such as these could now escape detection, if there were any writings of the same author or of the same age to be compared with them.

And ancient forgers were much less skilful than modern; they were far from being masters in the art of deception, and had rarely any motive for being so.
(b) But, secondly, the imitator will commonly be least capable of understanding or imitating that part of a great writer which is most characteristic of him.