What to look for in a shampoo bar?

I'm considering trying out some locally made shampoo bars, but yeesh! How do I tell the difference between a product that has legitimate and beneficial exclusions to their ingredients list, and ones that are caught up in (I'm so sorry if I offend with this) ridiculous hippy nonsense and are making exclusions/substitutions at the expense of a quality bar?

Like trying to find some craft shaving soaps, all of which proudly tell me how they are "palm oil free" and use olive oil instead.

What are some "must have" ingredients and what are sub par hippy/new age quackery substitutes to avoid.

I think what you're really looking for in a shampoo bar is detergent free. So no sodium laureth sulfate and the like. In which case any castile soap should do you (saponified olive oil/coconut oil). As for what you want in it I'd say whatever makes it smell good to you.

EDIT: Here's a thread where people are discussing the bars they like http://badgerandblade.com/vb/showthread.php/204086-Shampoo-Bars