Patchy models, could someone please help me?

[noxbox]

I haven’t been using Blender that long, and am following tutorials now.

I’ve tried making a glass shown in one of the tutorials, and followed the steps exactly, but the end-result was very patchy, unrealistic, and low res.

The glass has been sub-surfed and set to smooth. I tried simulating the effect of glass in my material, but I don’t think the problem is in the material, as the un-rendered, solid model also has these weird streaks/patches I didn’t design.

The rendered and un-rendered models are below.
rendered:

unrendered:

Does anyone know why this happens and how to fix it?

Thanks in advance

Attachments

[Richard_Marklew]

Looks like overlapping faces and inconsistent face normal directions

Remove any faces inside the mesh
Remove any duplicate objects that overlaps the target object
Remove any double vertices (select all and W / remove doubles)
Recalculate face normals (Select all and Ctrl+N)

Again check for any overlapping or duplicated faces. Select a vertex and face and move it to see if anything else still there