There are a number of reasons a film appear on dishes and glasses. 1) A ghost playing a prank. (Not probable, but can't rule it out.) 2) Your dishwasher needs to be cleaned. 3) Hard water is making things hard. 4) Something is blocking your chamber and/or there's not enough water getting to the detergent.
Fortunately, for you, we've mastered the art of dishwashing. (It's really more science than art, but you didn't come here for a chemistry lesson, did you?) Check out our blog post on ways to get that spot-free shine you so desperately crave and give your neighbors plate envy: https://www.trumans.com/blogs/blog/worstfilm