Ok, so there's no phantoms in your machine besides the usual malware and occasional user error. Some mmmm....mis.....mishaps (mistakes) that occur in drawing are due to the machine itself. There a number of very good tablet apps for drawing. It is hard to choose between them especially if you like the interface. I am talking annoyances here.
I was using Infinite Design, which is no drawing slouch by the way, to pull in one of my line drawings as a base image to trace over. Layers are a thing of wonder. The pen touches the surface and does it's thing, so does the edge of my hand resting on the tablet, in particular my little finger. It's like another person doodling on my doodle while I'm doodling. At it's worst you have to stop the flow of genius to erase the madness. Several solutions to this problem are on the market, one of which I have yet to try because there are certain personality enhancements attached to it, powerful, ooh!.........LOL!
Here is the problem in scientific terms. You as an electrical conductor have the ability, I mean capability or better yet capacity of capacitance with the surface of your tablet. That is why your finger works, and special pens and not your ball point. So if you are drawing with your special pen you have to hold it so that your fingers or palm do not both make marks on the screen. Ask yourself why the British, traditionally big on etiquette, hold their tea cups with the pinky extended, hmmmmm? Balance my man, balance and control. You couldn't possibly appreciate the nuances of the tea if you're gripping the cup like a mug. Unless it's a hot toddy of course. So on the market is a glove with the fingers cut off to reveal the capacitance yet cover the resting palm and I would hope the pinky. Don't worry about M. Jackson copyrights, archers, hunters, safe crackers all have variations of fingerless gloves. Can be very stylish, you don't have to be symmetrical and you could make your own glove.
Now the other solution is for the software to only allow one point of screen contact and better yet only the input of the special pen or stylus. Personally I think that should be built in to Android OS since it is a touch screen and stylus input OS. It's not because of user confusion. The Autodesk app for Android called Sketchbook Pro has a setting in the app to limit screen touch to the pen. This is great because I hate stopping to erase, undo and redraw when I'm on a roll. No more second hand drawing so your creative life is longer and better.
The other apps I use are Vector Artist and ArtFlow, they have the same problem as Infinite Design, too much touch. A glove might be better, a software switch is better yet. The phantom drawer is uncovered.