Acetone can damage certain materials like plastics. You'd have to be VERY careful of how and where to apply. Without acetone, you don't have to worry about anything, which makes the process go a lot faster.
I would not recommend to use a razor on your actual LCD. I do however, recommend nail polish remover (WITHOUT ACETON!!!) and a cloth. With windex it took forever, with the nail polish remover the residue came of in a matter of seconds. The added advantage is that it evaporates after the dirt has been wiped off the screen, instead of the oil you propose which will make your screen greasy and will not make the UV glue bond very well with the LCD.