Seeing a model from one view and notseeing it in another.

I think you might need to give a little more info, a screenshot or two would help :)

It sounds like the hair is made of single-sided polys with no "back", meaning that you only see the front of the polys. This article on backface culling should help explain why this might be happening.

If that is the case, googling " how to make double sided poly" might be of some use.

Or if Unity doesn't like double sided polys (I really have no idea if it does or not), you could mirror the hair or copy then flip it in your modelling program, this works well for mohawks but maybe not so much for other styles.

Before I forget, if you're seeing holes (the surrounding polys are fine, but a few are missing) then you just need to go into your 3d software and reverse the normals on the 'missing' polys, tha way the outside of your model will be actually interpreted by Unity as the outside and therefore be visible. If you do that to all polys that are invisible it should fix the problem.

Hope that helps.

Cheers

Sounds like something you need to fix in the modelling software, make sure textures and surfaces are facing the right way. Sometimes if you mirror a shape in a modelling software it comes out funny in unity.