I imagine the report padding strategies that theymos alludes too would be difficult to solve. Although, I don't think the consequences of users doing that is too bad. After all, it's a cosmetic thing. I personally don't see too many users creating alternate accounts, just to report their own posts. I feel like that would be too time consuming for a cosmetic benefit, although I might be putting a little too much faith into that if I'm being honest.

Even so, I don't think we'll be able to stop users from doing that, not easily.