I use the auto mode for 98% of the inventory photos I take. I also download the photos onto my laptop when I complete each room and if I find any that don't look good, I immediately retake them.
Since you said the lighting tends to be off when you use a photo cube. I suggest you set the "White Ballance" prior to shooting any photos. Also, you said they look out of focus. I suggest you have your camera looked at by a service person, as there could be a problem with it.
The only thing standing between me and actually doing an inventory for a client is my camera. I bought a Canon PowerShot SX10 IS a looooong time ago and it is my first camera that actually has settings. It has become a love/hate relationship because I cannot get consistently good photos. Either they look good on the viewfinder but are somewhat blurry on my computer screen, or the lighting appears bad, or they look just a tad out of focus. And when it comes to using a photo cube the lighting still tends to be off - it's hit or miss! I always use a tripod. Matter of fact I generally use the timer as well to ensure I don't even have my hands on the camera when the shot is taken. Now my question is this, what do most of you use when you take your pictures, because I know there are several different modes to choose from. Or do most of you just use the Auto mode? I am TERRIFIED of doing an inventory for someone only to find out that a lot of the pictures didn't come out good! I've never used anything other than a point and shoot. Aperture, shutter speed, ISO.. - OH MY!