Given scene/plot descriptions from movies or TV shows, and given a specific question about the scene, summarize the question into a title

[Q]: I notice that Trevor always cleaned his hands and toilet floor with bleach. He surely kept things clean at home that he always bought bleach, he kept several used toothbrushes to scrub his floor in detail manner, he kept notes at the fridge. But when he past his fridge when there was fish-blood leak on the fridge, he didn't notice the leak until his third passing.   What is the relationship between the bleach and the plot? Why didn't he notice the blood from the rotten fish when he was a bit aware of cleanliness? What is the relationship between the bloody and rotten fish inside the fridge (that he got when he went fishing with one of his co-worker) with the whole story?
[A]: What is wrong with the bleach and the fish in the Machinist?


[Q]: Hitler was definitely shot to death by the Basterds but he would have died in the fire anyways. Shoshanna had everything planned well to trap everyone in theatre including her, there was no escape. So when looking at this movie if the parts with the Basterds were removed her plan would have still worked. So were they even needed?
[A]: Did the Basterds actually change anything?


[Q]: Maria and Nicholas existed in Trevor's daily delusion because of his guilt about the past hit and run.   But how come Ivan exists in his imagination?   Are there any clues in movie that can prove Ivan's actuality in Trevor's past? Or is Ivan's figure totally delusional as in schizophrenic people?
[A]:
How come Ivan exists in the Machinist?