Trump has a very limited adjective repertoire. He seems oblivious to the fact that no one describes a phone call as “perfect,” but instead his perseveration of the statement regarding the call rather “perfectly” projects his guilt. 
His adjectives don’t deviate too much from all or nothing, black versus white thinking. He gets narcissistic supply or he’s injured, and that’s the extent of his engagement with adjectives — good vs bad, best vs worst, beautiful vs ugly.
“Perfect” represents the common narcissistic defense mechanism of splitting. Trump perceives himself as perfect, purely admirable and those not bending or conforming to his will, control or narrative are bad or evil.
His inarticulateness is multifactorial: the severity of his pathology leads to almost constant projection & reduced executive functioning especially under stress, neurodegenerative cognitive decline, suspected learning/reading disabilities & decades of not engaging in reading.
Narcissists with full cognitive function would never want to look stupid. They work hard to conceal & rectify behaviors that reveal their pathology. Trump has no insight due to the severity of his narcissism and some type of neurodegenerative or organic cognitive impairment.
