Plot Summary and Wordiness
Throughout Hawthorne's The Scarlet Letter it is shown that Dimmesdale conceals his sins about the adultery that he committed with Hester. This takes its toll on him both mentally and especially physically. (32 words)
The above is a perfectly acceptable introduction to a pro/con paper, though I'd rather see a more forceful opinion. Before I get to that, however, I want to address over-emphasis of plot summary and wordiness. In this case, the two problems are related.
Your audience for a college literature paper is first and foremost your instructor, but by convention you are expected to write for any interested reader who is already familiar with the details of the major work you are discussing, and who has a copy within reach to consult. The first sentence quoted above does a good job of quickly introducing the focus of the paper, but it includes extra unnecessary details.
Dimmesdale conceals his sins about the adultery that he committed with Hester. (12 words)
Nobody who has read The Scarlet Letter needs to be reminded with whom Dimmesdale has sinned, or that the chief sin in question is adultery. If the paper were to go on to suggest Dimmesdale commits other sins -- pride, misleading his congregation, abandoning his own daugther, etc. -- then it might be worthwhile to list those sins. But in a paper that is chiefly about the adultery, the core of this sentence is all that we need.
Dimmesdale conceals his sins. (4 words)
Well... so what? That's a more efficient introduction of the paper's topic, but at this stage, when stripped of the detail, it's a non-controversial, simple statement of an important plot point.
Throughout Hawthorne's The Scarlet Letter it is shown that Dimmesdale's concealed sin causes both mental and physical suffering. (18 words)
Nothing is lost if I revise the sentence thus:
Hawthorne's The Scarlet Letter shows that Dimmesdale's concealed sin causes both mental and physical suffering. (15 words)
But again... so what? Where's the non-obvious point that needs to be argued? What's a reasonable alternative point of view?
Reading Hawthorne's The Scarlet Letter strictly as a novel about the moral angish of concealed sin ignores the fact that Dimmesdale also suffers physically. The intellectual bond between the minister and the sinister contrasts with the painful but potentially redeeming spiritual bond between Dimmesdale and Hester. Since Dimmesdale is more threatened by Chillingworth than he is by Hester, the novel suggests that Hawthorne is less bothered by the old power of religion than he is by the new power of science.
Now we've moved from a statement that identifies two kinds of suffering (defining and identifying are low-level skills, according to Bloom's Taxonomy), to a provocative claim that says one kind of suffering is more important to the novel than the other (and evaulation is a higher-level skill).