The idea that Rousseau set out to present a vision of himself that strove to be "true" was probably the most scandalous aspect of his work. He seemed to have little problem depicting himself in an unflattering manner. He openly displays behavior in the work which shows him to be capable of lying and stealing, reflects sexual attitudes that were contrary to the social norm, and shows himself to be an individual that is does not "conceal of any crimes." It might be in this realm, in general, where Rousseau's work could be seen as "scandalous" given the time period. Rousseau might have been one of the first thinkers/ writers to understand and actually enjoy the notion of "shock value" in the composition of his work:
Any other autobiographer would have suppressed such unflattering incidents, and Rousseau chides Michel de Montaigne, famous for his honest self-portrayal in his Essays, for having included nothing comparable. If Rousseau’s facts are not always verifiable, his candor is certainly genuine.
Rousseau did not shy away from displaying himself in a manner that is almost reprehensible, such as the framing of a servant girl or his submissiveness to women, bordering on almost fetish- like. At a time when literature was driven to display moral purity reflective of the reasonable nature of human beings, Rousseau's work displays something else. This might be reason enough for it to be considered "scandalous."