It has variously been claimed that the Codex Astartes was composed by Roboute Guilliman, Leman Russ and Rogal Dorn. The contents have varied too: while modern Space Marine imagery makes almost no use of camouflage, this was originally held to be advised by the Codex Astartes (although ignored by many Chapters) and many contemporary Space Marines of the game's early years wore camouflaged armour.
I don't have the books with me but you can check the quote
here.
@Trov - calm down a bit. I think you're overreacting. if you don't want your minis to be commented, why do you show them to people at all?

nobody said your minis aren't good, people just told what they wolud like better. i think it's a normal thing... you presented so many top-quality works, that if people see something a bit weaker (even if it's still better than many minis we see) they are surprised. live with it, take it as a compliment
People are talking mostly about their tastes - do they like the actual trend of paining freehands or not. I think that freehands are a great methods of showing one's skill. the other thing is taste - one person will like it another one won't. well, that's normal IMO. i would also prefer to see freehand painting "justified" by fluff, story, reality, etc. but if one does it even just to demonstrate their skills - that's ok. their choice. but not everybody has to like it, right?
as for the SM freehands, I don't think they're a bad idea. SM armour and stuff is revered and treated like ancient objects of cult. These are like sacred items, and they are often of cancient origin, so why should it be criticized? If the SM believe their faith will protect them, why bother with camo. OTOH (just like it was mentioned in the quote I used in the beginning of this message) it was mentioned that SM used camouflage and there are pictures which can be used as confirmation. now you decide if your faith is strong enough
