That is hardly ‘plain and simple’; in fact, it is ambiguous. Do you mean “I cannot discern a meaning to this sentence” or “I understand this sentence, and I evaluate it to be false”?
As for “fair criticism”, try for something that, if it were said to you in that position, you would reply to it with a ‘fair enough’/‘you make a good point’.
That is hardly ‘plain and simple’; in fact, it is ambiguous. Do you mean “I cannot discern a meaning to this sentence” or “I understand this sentence, and I evaluate it to be false”?
As for “fair criticism”, try for something that, if it were said to you in that position, you would reply to it with a ‘fair enough’/‘you make a good point’.