Am I Normal 'Down There'?
Can that paper crotch guard in bathing suits prevent disease from spreading?
You're on to something here: it can't. The paper just protects the garment from getting stained. It doesn't protect you from nasty infections or pubic lice.
So you must always wear your underwear when trying on a bathing suit-it's lumpy, yes, but necessary. And once you find your perfect suit, wash it in warm or even hot water before wearing it.