I think if people read and understand the sticky
How To Know if Your Games Ready For A W.I.P Post, then it is pretty obvious whether your project is ready or not for a WIP post. It is common sense. But some people just don't have it, I guess.
We can try to make a hard/fast rule that will weed out the bad ones before they ever take off into a blaze of flames. But I don't think setting a specific percentage is the way to go as mentioned already, it is too subjective.
The forum is a visual medium so at a minimum there should be screen shots. Not only will it keep people's interest but it will help prevent the "idea posts" that crop up once in a while and belong in the game design forum. Screen shots do not mean screen captures of a 3D model in the modeling software. It means the game itself.
A good description of the game should be a requirement. If someone can't write more than 2 lines about their game then what is the chance it will ever go anywhere?
A demo is frosting on the cake, but shouldn't be required if decent progress is being shown (in form of more screen shots or videos).
And WIP needs to be made with a TGC product: whether it is DB, DBPro, DarkGDK, T3DGM or whatever. I'm a little annoyed at the recent posts of RealmCraft, GameMaker, and NG projects. How obvious is it to everyone what this forum is about? People don't seem to care...
With that being said, the above aren't really hard/fast rules (except screen shots and TGC product used)... maybe what we need are more MODs on this forum. Maybe they could be mini-MODs that are just assigned to the WIP board if that is possible. Anal retentive people who are stickler for the rules would be best. I'll volunteer!
I'm not a real programmer but I play one with DBPro!