For those who are having issues with a shiny Roadhog, I've found your fix. Mind you, this isn't a PERFECT fix, but it's a fix that works, and it'll require you to work a little!

1. Load the model(s).
2. Right click the model in Animation Set Editor and select "Add Override Materials"
3. Right click the model again and select "Show in Element Viewer" > "Model"
4. Go down to Materials.
5. Right click leather and select "Add Attributes" then click Vector 3.
6. Where it says newAttribute replace it with: $envmaptint

You will need to do this for the following materials:

• Main Roadhog Model: leather, metal, plasticpad, back_gun, grinds, breather, gold, mask, and shoes.
  
• Roadhog's Gun Model: gun_metal
  
• Roadhog's Hook Model: hook
  
  If my solution worked for you, then success! :D <3 Enjoy Roadhog. If not, you can try the following:
  
  
• Type "mat_reloadallmaterials" (without the quotes) into the console.
  
• Load the model, save, exit out of SFM and reload SFM.
  
• Click Enable Lighting twice.
  
  While I found the other options didn't work, my solution worked for me, it just required a little extra effort!
  
  If you have ANY questions don't hesitate to ask! This also works with other Overwatch models that have this issue, it's just a matter of knowing which materials are having this shiny issue! The best part about this is, if you do try it on a material and it's not the right one, no worries it doesn't really change anything from what I've noticed and if so Ctrl + Z is your Undo friend. :D