i've found the solution. I have an iPhone 5s. Like everyone else having this problem, it all started with a replacement touch screen, aftermarket screens or bad screens seems to have an awful or nonexistent oleophobic coating. In my case seems to have it, but within weeks it just disappears and the iphone start ghosting, so i figured out that must have been a screen issue. The solution? I just bought a cheap template gorilla oleophobic glass cover, and so far, the ghosting touch has gone.