Alright, so, if you find an app, and you do not know the person?
Well! I have a solution!
Don't post in that app (including +-0 it's stupid imo) until you know them.
Posting -+0 is fairly pointless IMO, it's kinda self explanatory why, but this is the internet. If you post -+0 you're not actually giving an opinion on the player and weather he should be promoted or not. It's simply saying that you have no opinion on the player, or you don't know him. The whole point of allowing for VIPs to post on VIP apps and community to post on Reg apps is so that the community can give their opinion on the player, and maybe persuade them with it.
TL;DR
It's pointless to put +-0 on apps and therefore, IMO, a +-0 smiley would be pointless as well.