Poo on No Poo?

Over the course of a few months, three bloggers I follow all discussed using baking soda instead of shampoo and vinegar instead of conditioner. As I read the sources they referred me to I found confusing-- even confused-- advice.

For starters, nobody really seems to agree on the ratio of water to vinegar. I saw everything from 6:1 to 1 cup:1 tbsp (16:1) to no vinegar at all (divide by zero error).

Next, there was disagreement on how to use them, including some impossible instructions.

1. Use baking soda only on the scalp, and vinegar only on the tips of the hair. I don't see how this is going to work if you have more than three hairs per square inch of scalp, at which point I would just shave my head. I guess if your hair is long enough, you can effectively reach this goal...
2. Use baking soda on the scalp and hair, but vinegar only on the hair ends.
3. Use baking soda only on the scalp and vinegar on the hair.

So... which is it, and why?

But my absolute favorite advice was to never get both on your hair at the same time. "This would be really bad." OK... why is that? Because you once saw a fake volcano made with these ingredients? Are they afraid of the carbonic acid created? Vinegar is already acidic, and in any event, the carbonic acid immediately breaks down into carbon dioxide and sodium acetate (which is safe for human consumption).

Meanwhile, I'm in that inbetween place some people hit while their hair adapts to a new regimen. Since I have longish (2" to 6" depending on where on the head) hair and can't really get away with Snape hair, I use a small amount of shampoo (just on the hair!) every 2-3 days.

So... can anyone point me to something definitive on this stuff? If I can't get away from shampoo as a cheater step soon, I'll probably give up and go back to using post-industrial waste on my hair. Someone help me!