As has been mentioned, generally there is no danger from a surface film or slightly cloudy water when this latter is a bacterial bloom caused by a water change or cleaning the filter. When occurring following a water change, it might also be sediment in the tap water which can vary from season to season depending upon the weather and the source of the water.
With the surface scum, you do want to keep it down, as it can thicken and prevent the necessary gas exchange (oxygen/carbon dioxide) at the surface. I find the easiest way to remove it is to invert the water changer and hold it just at the surface so it sucks out the water with the scum. There are two types of surface film, a protein bio-film caused by organics, poor water circulation (primarily at the surface) and maybe low CO2; this is somewhat greenish in appearance and doesn't break up if you put your finger in it. The whitish film which will break apart with your finger is an iron bacteria film and more surface movement usually deals with this easily.
Byron.