as long as every single page is still inside it and they are undamaged, you shouldn't have a problem.
there shouldn't be an issue as long as the cover is still in one piece. An invalidated passport can have the corners clipped off it as a clear and visual marker to show it isn't, but the print in the cover isn't really of any importance.
sitting right now with a German national, he insists the only time he's seen Germans clap was on a private charter flight. Austrians and swiss the same, no clapping.
never been on a UK flight where people have felt the need to clap. never been on a flight filled predominantly with Western Europeans where they have felt the need to clap. Been on several flights to and from the Philippines where passengers have felt the urge to clap.