I don't think this is any different than other types of marketing. In the short term, most of what you do will have a small impact and whether you go with a more "shady" strategy or a totally kosher one won't really make a difference. In fact, in the short term, the shady tactics might even perform better. But the kosher route will typically do much better in the long run. I won't give examples unless someone disagrees, but there are plenty of them.
Anyways, I think the same idea applies to this tactic. Maybe buying likes would make your page look more credible in the short run, but if you take the time to build a real social following you will have better engagement and your work will have a greater impact in the long run.