Bad effects are bad.
I used to hate film grain and then did the research for implementing myself, digging up old research papers on how It works at a scientific level. I ended up implementing a custom film grain in Starfield Luma and RenoDX. I actually like it and it has a level of “je ne sais quoi” that clicks in my brain that feels like film.
The gist is that everyone just does additive random noise which raises black floor and dirties the image. Film grain is perceptual which acts like cracks in the “dots” that compose an image. It’s not something to be “scanned” or overlayed (which gives a dirty screen effect).
Related, motion blur is how we see things in real life. Our eyes have a certain level of blur/shutter speed and games can have a soap opera effect. I’ve only seen per-object motion blur look decent, but fullscreen is just weird, IMO.
Most “film grain” is just additive noise akin to digital camera noise. I’ve modded a bunch of games for HDR (RenoDX creator) and I strip it from almost every game because it’s unbearable. I have a custom film grain that mimic real film and at low levels it’s imperceptible and acts as a dithering tool to improve gradients (remove banding). For some games that emulate a film look sometimes the (proper) film grain lends to the the look.