Martin (1992: 580):
[7.5] Mother: Don’t do that…Now look, you’ll get it all over me Peter: (Laughs) Mother: It’s not funny. What’s funny about that? You do it again and I’ll whack you.
As Cloran points out this example nicely illustrates the variable nature of semantic styles as tendencies, not rules; the mother in 7:5 appeals to both an inherent consequence (You'll get it all over me) and a threat (I'll whack you) to control her son (the text is in Bakhtin's terms, dialogic — it realises more than one voice; his dialogism can thus be seen as a natural implication of any text based on semantic variation).
 This confuses variability in the linguistic realisation (semantic style) of one coding orientation with the different linguistic realisations (semantic variation) of different coding orientations. The notion of a text as "based on" semantic variation derives from this misunderstanding.
 Martin's claim here is that because the mother uses two different linguistic realisations of her coding orientation to control her son's behaviour, the text realises more than one voice, and that this makes it dialogic in Bakhtin's terms. This misunderstands the terms 'voice' and 'dialogic', as formulated by Bakhtin. The glossary provided in Bakhtin (1981: 434, 428, 426) clarifies the distinction between them, and how they differ from heteroglossia:
This is the speaking personality, the speaking consciousness. A voice always has a will or desire behind it, its own timbre and overtones. Single-voiced discourse is the dream of poets; double-voiced discourse the realm of the novel. At several points Bakhtin illustrates the difference between these categories by moving language-units from one plane to the other — for example, shifting a trope from the plane of poetry to the plane of prose: both poetic and prose tropes are ambiguous [literally "double-meaninged"] but a poetic trope, while meaning more than one thing, is always only single-voiced. Prose tropes by contrast always contain more than one voice, and are therefore dialogised.
The base condition governing the operation of meaning in any utterance. It is that which insures the primacy of context over text. At any given time, in any given place, there will be a set of conditions — social, historical, meteorological, physiological — that will insure that a word uttered in that place and at that time will have a meaning different than it would have under any other conditions; all utterances are heteroglot in that they are functions of a matrix of forces practically impossible to recoup, and therefore impossible to resolve. Heteroglossia is as close a conceptualisation as is possible of that locus where centripetal and centrifugal forces collide; as such, it is that which a systematic linguistics must always suppress.
Dialogism is the characteristic epistemological mode of a world dominated by heteroglossia. Everything means, is understood, as a part of a greater whole — there is a constant interaction between meanings, all of which have the potential of conditioning others. Which will affect the other, how it will do so and in what degree is what is actually settled at the moment of utterance. This dialogic imperative, mandated by the pre-existence of the language world relative to any of its current inhabitants, insures that there can be no actual monologue. One may, like a primitive tribe that knows only its own limits, be deluded into thinking there is one language, or one may, as grammarians, certain political figures and normative framers of "literary languages" do, seek in a sophisticated way to achieve a unitary language. In both cases the unitariness is relative to the overpowering force of heteroglossia, and thus dialogism.