I have a black anodized or painted ivogo cloned cherry bomber, I've had zero issues with auto firing, even using a black anodized hellboy square atty that touches the box. I think the fact they are both coated to some extent is insulating enough to prevent it. But I do have a huge issue with it not wanting to fire consistently. I have replaced the spring with MCV magnets. It fixed a hot button issue but i still get intermittent firing. I removed the button and took a dremel with a burring bit on it and smoothed the contact area where the switch meets the box, but its still a PITA. I have to take the thing apart every time I put a new atty on because the flat spot on the copper ring around the 510 gets out of position. The CB hits hard as all get out when its firing, but I keep searching for a permanent solution to ensure a proper fire. I've pretty much given up on it and just have it laying around for when I want to get aggravated while vaping.
Update: Anyone having issues with firing, go buy some brasso from your local hardware or department store. I cleaned every contact point with brasso and it's firing perfect, not sure how long it will last, but hopefully this will help others. Brasso is cheap and cleans copper, brass, SS and more very well.