I would say that the use of figurative language is critical to its particular application to a specific audience. The imagery of a work, for example, conjures up mental pictures through words that can be understood by audience members. The ability of these images to be appreciated comes from the fact that certain audience members will understand the force of such pictures. Another element of either poetry or any work of literature that can be appreciated by specific audience members would be tone and/ or theme. If the meaning or purpose of a work is designed with a specific relevancy, the reader can gain better insight as to who the intended audience was in terms of meaning and relevancy to those specific readers.
This is a very difficult question to answer, not because it is irrelevant or vague because it has so many ambivalent aspects to it.
First and foremost, is there an intended readership or audience in the mind of the author at the time of composition? The idea of the 'target audience' works in definitive genres like high art, low art, children's literature and so on. But in today's postmodern literary world, when high and low art forms are mixed up and all genres deconstructed, the very idea of a 'target audience' is in shambles. Secondly, the figuration of the authorial intent is not something that we talk about these days. The text is seen as an independent body, instead.
But with reader-response theory, the role of the audience has really been foregrounded especially in the cognitive act of completing the authorial meaning if there is one at all. The technique of the inbuilt reader is used in many of the contemporary works and that characterization can give he readers some idea about the intended audience.
Apart from this the style or the content of a work, the motifs involved the kind of characterization, the language in which it is written basically depending on the order of difficulty sometimes do give us a rough idea of the kind of readership, for which it is meant.