I mean when he transforms into Red Hulk, his mustache magically disappears as he is clean shaven.

What's the logic in that? does it go in his lips or do the hairs fall off then when he becomes Ross again the mustache grows back?

It's as bad as the same thing on Trial Of The Incredible Hulk

@Jakesully1981:

It appears that his mustache recedes into his skin, however, I personally think he sheds it off, then regrows it when he reverts back into human form. Just think of how a werewolf grows fur when it transforms, but reverse the process.

It goes to a place where only cool mustaches can go.

I don't know about Rulk's magical moustache but it's no where near as awesome as Colossus's metallic beard!

Pocket dimension.

Great question.

Ross having a mustache in human form but not in Rulk form is lame.

It goes to the same place where Hulk gets his purple pants

@PowerHerc:

I guess it makes more sense now as his possible-alternate future self has a mustache.

Then again, the future one looks like he might have a suit on, so....yeah...

http://www.comicvine.com/news/off-my-mind-why-doesnt-hulk-ever-have-a-mustache/142464/

I also asked Mark Waid:

http://www.comicvine.com/news/interview-mark-waid-on-indestructible-hulk-daredevil-and-hulk-mustaches/145238/

CV: Where doesThunderbolt Ross' mustache gowhen he turns into Red Hulk?Will your Hulk ever have a mustache?
MW: Thunderbolt’s mustache goes into the Negative Zone, where it enjoys its own separate adventures that will hopefully someday be told. Our Hulk needs no mustache. Muttonchops, perhaps.

Well future Rulk has a mustache as seen in A+X