What are you importing them from - i.e. software what were they created with. It's been a while since I worked in 3D land but it looks like half of your normals (every other triangular polygon) are pointing the wrong way. Do you have the option of creating two-sided polygons?

Do you have an image of what it should look like?

It should look solid! It is a .dae file if that helps - could it have something to do with per pixel lighting - is there a shader I can use to smooth that stuff out?

without seeing your model file, it's hard to say. i second the above diagnosis of a problem with reversed normals. you have to fix that in your modeling software.

does it look correct when you draw it without the material applied?

Yeah, these are just bad models - ill try higher poly models next time, thanks for the help!