Do you know about distinction - and it's a useful one - between communication that tries to reinforce and communication that tries to get change?
If you follow politics you'll already be familiar with this idea: Incumbents send messages that reinforce existing voter behavior, while challengers call for changes.
Any thoughtful marketing communication (and political communication is marketing communication) will be strongly influenced by this distinction, which affects not only content, but also presentation, and perhaps even medium.
For example, suppose you own a bookstore and every couple of months you send a newsletter to all residences within a two mile radius.
Now, if you have good market share and you're profitable, you won't want to rock boat. You'll want to reinforce existing behaviors (which include buying at your store).
On other hand, if you just opened a new bookstore and need to take market share from other bookstores, then you want change existing book buying behavior.
Another example: Suppose your employee safety program has worked well for past year and you want to maintain practices that led to this longest-ever period without an accident. Your communication would reinforce. On other hand, if safety record was unacceptable, you would try to get change through your communication.
In a change situation, we want to upset status quo, to challenge existing beliefs and ways of doing things. That means words and style could be somewhat inflammatory.
We can do this by making bold claims or allegations: Just listen to, or look at, advertising claims like these: "If you shop at Joe's Bookstore, you may be paying too much!" or, "Drive a bit further and save a lot more at Jane's Bookstore!"