Skins pretty much always have to go, same goes for parts of the storyboard that puts me out of rhytm. However, while a lot of people seem to frown upon storyboards with flashes/pulses i find that they do, if timed correctly, both makes the map more enjoyable and makes me play better.
What I find interesting however is that you ask not only about backgrounds, skins and storyboard elements, but also storyboards themselves. I always assumed there'd be some kind of serversidedcheck to assure you were using the correct one, but since you have to ask, does that mean that you do actually not make sure that the correct storyboard is used, and that the only thing stopping anyone from completely combating the hidden, and partially combating the flashlight mod with a custom SB, is the amount of time they would have to invest?