I delete stuff if it bothers me while playing.
Examples:
Massively flashing SBs like http://osu.ppy.sh/s/17670 or 90% of Nightcore maps
Skins where I can't read elements correctly (for example if the combo number blends in with the hitcircle overlay or the score sprites are too similar/not intuitive to me) - prime example for the second case: http://osu.ppy.sh/s/18191
Also, Spinners where you can't see the center since I have the awful habit of spinning in way too small circles and I fail spinners if I don't see the center
Backgrounds only if I can't see the hitcircles properly - mostly Jumpmaps with weird patterns (http://osu.ppy.sh/s/21877) or sometimes maps with AR9/10 but there are some maps where the combo colours just blend in. Ephemeral's Bad Apple, I'm looking at you :<
Examples:
Massively flashing SBs like http://osu.ppy.sh/s/17670 or 90% of Nightcore maps
Skins where I can't read elements correctly (for example if the combo number blends in with the hitcircle overlay or the score sprites are too similar/not intuitive to me) - prime example for the second case: http://osu.ppy.sh/s/18191
Also, Spinners where you can't see the center since I have the awful habit of spinning in way too small circles and I fail spinners if I don't see the center
Backgrounds only if I can't see the hitcircles properly - mostly Jumpmaps with weird patterns (http://osu.ppy.sh/s/21877) or sometimes maps with AR9/10 but there are some maps where the combo colours just blend in. Ephemeral's Bad Apple, I'm looking at you :<