Final answer:
The sentence uses insinuation as a rhetorical strategy, casting doubt on the subject without evidence and demonstrates a limited rhetorical awareness. The strategy is not effective in engaging with the reader or addressing potential counterarguments.
Step-by-step explanation:
The rhetorical strategy used in the sentence "For some reason, President Obama has never shown his birth certificate" is one that suggests insinuation or innuendo.
This strategy is employed to subtly imply something is amiss or to cast doubt on President Obama's legitimacy without providing evidence, thus capitalizing on the reader's suspicions or predispositions.
It shows little evidence of rhetorical awareness and does not engage with potential counterarguments or appeals to logic and emotion in a rhetorically effective manner.
Additionally, the sentence does not demonstrate the writer's intent to either meet or challenge conventional expectations in rhetorically effective ways, showing limited variation in sentence structure and a lack of engaging dialogue or action.