Here’s the thing: if a customer didn’t share your deal on Twitter or Facebook, there is probably a reason. Maybe you made it too hard (strong inhibiting pressures) by not having a simple share button. Or maybe they just didn’t think your deal was worthwhile enough (weak promoting pressure) to waste social capital annoying their friends with (strong inhibiting pressure). Either way, it isn’t an accident.
If it was just strong inhibiting pressures, you can easily address it: add the share button and be done. And if the promoting pressure was too weak, you can give a gentle nudge in that they may just need to be reminded that it is an option. What you don’t want to do is pay them.
In psych terms, what you’re doing is raising the promoting pressure: you’ve paying people to get over the inhibiting pressure of actually sharing something and annoying their friends with it, which has the obvious drawback. But more importantly, you’re also paying people for something that they are hypothetically motivated to do anyway, which brings in the overjustification effect.
Basically, when you are paying people to tell others about your brand, you are replacing any intrinsic motivation they might have (actually liking your brand) with an extrinsic motivator (money). So you’re actually shifting the “why” of their actions and how they justify things internally. This isn’t problematic…until you stop paying them. Because you wiped out any intrinsic motivation with your payment, the moment you stop handing them money to talk about you, they’ll both stop doing and stop having positive feelings about your brand.
So this is a short-term gain play. Sure, you can grab some new followers by spreading the word and spending cash. But ultimately, you undermine the very thing you were trying to build: brand awareness and loyalty. What you want is authentic motivation, and you can’t buy that with straight money (though you can spend money on programs that encourage it). Which is what more brands should do, instead of pumping money into things like PowerVoice.