I also want to add that some fx can be used as basic instruments, turning to be percussive and even a leading instrument. I don't think there's any rule about it, as I said, if you integrate it cleverly within the theme. I come from film-music, so the use of waterphones and other fx is very very usual, and almost the law and not the exception. In terms of the standard pop-rock hit I should not say as it's not my field.

Priscilla Hernandez singer-songwriter
http://www.yidneth.com
New album at:
http://theunderliving.com