I noticed that robbing some house interiors, even with people present, no one reacts. Of course, i steered clear of guards and packages near them.

Is there any safe looting pattern? All materials are very expensive to buy, sell for very low to sell and even the tiniest bit of loot picked from around is useful...

Loot everything that's not nailed down. The game warns you when you're about to steal. In Witcher Sense mode you'll see a little white hand above the container if it belongs to someone. I've stolen from those too.

I'm level 16 and I've only had one warning in the Nilfgaardian camp that guards were watching and I shouldn't take the items. Other than that I've looted every single container I've seen.

Great news you bear! I will leave NOTHING! Scoop everything up! What dumb system that one about theft, 1 and 2 were so nice, considerate to the player and playerfriendly...