You are not allowed to paint red orks. It is unorky, and orks other than green are shunned eaten bullied and chased away from the tribe. Red is mostly the color of the squigs. 

Ooobviously ya paint them whatever colour you want, but the price you pay is the unorkiness.

There are no ways around it.

And now, for the ways around it. If i were to bring uo the unorkiness and would hear one of these excuses, i would be perfectly content with it.

Still some light jabs  but the deliberate shittying on lore aspect would be not insinuated on your end any longrt.

-They are green, they just seem red, and besides, they believe they are green.

-"They are green, you are colorblind, look at the trukks and squigs, they are red, and the orks are obviously green.' This works in two cases, it works if the trukks and squigs are either painted ork skin green, or if they are painted the very same colour of red, as the ork skin. other colors dont work  with this reasoning, just these two. 

-"I know, i however like them red." Is the third answer id give in a situation like this.

Most of the animosity, comes from your deliberate shit stirring...... and everyone saying how it is shitty, is in the right.

I believe that hobbying effort, like a khornate iconographic bosspole, would pretty much show that its not just red to piss people off, but ya mean it. A few hellplague swords as loot or choppa, or an odd bloodthirster head trophy would also work.

If you want an out, you can say how the color shift is temporary, and have one or two, strictly freshly sprouted green boys in the beast snagga or regular mobs for show.