Most GMAT candidates are native English speakers. So SC is not a test of English as a Foreign Language. Rather SC explores the gap between casual spoken colloquial English, with all its errors, slang and contractions, and formal written English.
Candidates who believe that their “good ear” for English is sufficient, will get SC questions wrong. Adopt instead a checklist-based approach. Consistently and “robotically” applying a handful of rules will successfully defeat most SC questions.
This is not the occasion to display your general or specialist knowledge. Candidates who stray outside the boundaries of the passage will get questions wrong. Adopt a forensic approach to individual words, linking words in the questions to usage in the passage. Don’t draw executive conclusions or read between the lines – just the facts.
This is Logic 101. The “fact situations” described are irrelevant – look through the “story” to perceive the abstract underlying structure of elements-linked-by-relationships. Candidates who treat CR questions as business cases, exercising their commercial judgment or common sense, will get CR questions wrong.
Generally three of the answer choices are easily dismissed for being “off-topic”. One answer will be “almost right”: that one is wrong. The correct answer may not appear intuitively promising in a real world sense, but CR is about cold, abstract logic.