Well, the basic fact is that Mirror Image has no save. There is no way for you to "disbelieve" the images.
That's because the images vanish as soon as something strikes one of them. There is an inherant weakness built into the spell. If you could disbelieve the images, then the spell wouldn't be useful at all at higher levels. As it stands, Mirror Image is a wonderful wizard defensive spell. Why you want to take that away from them I have no idea.
I admit that it might not fit in the rules, and you are right... most glamers do allow saves. But Mirror Image is an odd spell rule-wise, and pretty unique, so it's no surprise.
Look at it this way... if you have access to a magic item that grants True Seeing, you are immune to the effects of Mirror Image, or you can simply CLOSE YOUR EYES.
Yup, that's right. Close your eyes. You are subject to the 50% miss chance, but if the wizard has 8 images, your odds are much better when blind than trying to figure out which figment is the wizard. If you intentionally blind yourself, you have no chance of hitting a figment, you only have a 50% miss chance period.