hi there,
is this a roll vinyl floor, or vinyl tiles.
there is a possibility that if it is a roll vinyl floor,
the question is have the black marks just started to appear?
ive seen this in the past, where unkown to you, moisture has got underneathe the flooring and the black marks start to come through the floor.
if however you can feel the balck marks on top of the floor, ie scuff marks, then these should lift.
regards
martin