さも

さも strengthens how something looks: "with every appearance of", "as if". It goes before 〜そうに or 〜げに ("looking ...") or before 〜かのように ("as if ..."), and the phrase describes the way someone acts or looks.

さも〜かのように

With かのように, the appearance and the facts part ways: the person acts as if something were true, and the speaker suspects it isn't. This is where さも is most often critical.

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さも belongs to writing – novels, essays, reporting – and to speech that is telling a story. In conversation, いかにも does the same job before 〜そうに.

The set phrase さもありなん is classical and means "no wonder", "that figures". You meet it only in writing.