I am not one for deleting map elements. But I often replace them with a properly colored/better/easier to see ones. Or sometimes replace a normal video with another of a higher quality. Some backgrounds are really difficult to tolerate, being in a household with three children under ten years of age, those I delete/replace with similarly colored,"Safer" ones. Though, to be honest, I could also live with not being able to delete or change anything -- it will not make life much harder, I would simply have to disregard such maps/give them a low rating for their inability to provide a level of entertainment that reaches all ages and is unrestricting to play. (I sometimes try to suggest better options to the "offending" mapper when feasible)
Update: I rename map elements only when trying to play something with HR or DT. It makes everything easier because I can then read the followpoints, so I can read the map a lot better. I'll put it back when I'm done though.
(Now I completely understand why a lot of pro players delete stuff, HR and DT are practically impossible if you add a BG~ o.o)
I also don't delete... I put troublesome elements in a bak directory, which makes it easy to restore as well as find the maps I've changed.
1) Flashes. Most maps with the warning I have no problem with (I'm not epileptic)... but a handful hit me pretty hard with nausea and disorientation, which can still be effecting me an hour later. After it happened the first time I've become more proactive with removing flash images from maps at the first sign that they might effect me.
2) Can't easily see some or all of the approach circles (because if I didn't want to see them, I'd turn on Hidden). On some maps, it's because of the circles themselves... thin or partially transparent. A lot of the time it's because of one or two combo groups which blend too well with the background... sometimes its pastels on pastels, but a lot of the time it's a dark colour (typically near black grey, purple, or blue) on a dark background. A lot of the time I put up with it, but I really hate it. If there were controls to alter combo colours in the game, probably be using them a lot.
3) Things I think are just pointless... like replacing the combo break sound with a silent one.
Most other annoying stuff I put up with.
I will also admit that I have been tempted to do what others have suggested like replacing videos... either with higher quality ones, or with different videos (like replacing some of the Bad Apple videos for other versions just for variety). Similarly, there are a number of maps that use the same background (or no background)... I've been tempted to change some of those.
In most cases if the bg is very detailed (i.e. lots of colors, or other details) I will delete it in a heartbeat. If it's a more simple one, then it all depends on the combo colors if I delete it or not. All SB (unless it's really subtle) get's deleted instantly as well. And I want to use my own skin only, so in 99% cases a skin which uses too detailed hitcircles and/or a custom hitburst skin, it just has to go. ;x;
I hate bright bgs, they are a huge pain in the butt. I like my custom skin which I made myself, I am happy with it, thank you, don't force me to play a TOUHOU or default skin EVER again, please... I beg you. But if you really, really tried your skin on all diffs not just easy, and you found that awesome, you skinned it and made an awesome SB which is helpful and not being an offense to my eyes then yes, I won't delete it. Until I put HR+DT there.
Pretty sure most top tier players delete everything as it has a big impact on ur gameplay, and so do I , I'd rather have better gameplay instead of cool looking (he says hoping not to see forced bgs on osz2 : P)
Deleting everything, especially crappy skins that gives a weird feel to the gameplay. (one map had an 8-bit pokemon skin, that was when I started to delete everyting)
wether i'm playing competitively (solo) or casually(multi), i awlays have my song folder open so i can delete_every_single_visuals. any form of visuals that aren't essiential part of the gameplay should not be there in the first place. i don't delete custom histounds tough.but mostly beacause they never bother me,not beacause i like them.
Im playing with a blank background(black). I just rename it the title name for ex: 'BG' changed to 'BG(space)asdassadasd' instead of delete the BG, SB or other elements