Julius_SteezerOk, I was kinda hoping you specifically would answer my question so thanks very much for that.
So unsurprisingly, I was asking as there's a bargain boot online. Its on eBay and fortunately, the guy doesn't live too far from me so I was gonna go round and see him about them. I am not a bootfitter and don't pretend to be but these a brand new ghosts for £20 (I don't know if its too good to be true which is why I wanna go round and see them). Could I check the shell contours myself (are there any obvious things to check for?) or is it only something you can get from years of experience?
For 20 quid, why not?
First start with a length wise shell check: remove the liner, step into the shell while wearing a thin ski sock, slide your feet to the front so your toes barely touch, and measure the space behind your heel. A race fit is 1cm, normal is 2cm, too big is 3cm.
Next, check the width. With your foot centered in the shell, about 5mm-10mm away from the back of the heel, examine the space on the outside of your foot. If your foot contacts the shell, it is way too narrow and you will need to stretch it in the area which contacts your foot. Normally, you want to get a finger tip between you and the shell (this mimics the liner thickness). You can also do this test for the inner ankle and navicular bone.
With these über basics, you can see if it might
be a good starting point for you. Other tests will be more complicated but if the boots are in good shape, you can take them to a fitter who will charge you a small fee to take care of the rest.