In normal sex the vagi-nal walls can produce lubrication by themselves but as the person ages the lining of walls starts to thin and they are not able to produce as much of lubrication as before but thats normal as the sexual drive also lessens with age.
Moreover the normal sex organs have a natural cleansing system called uri-nation

Moreover frequent an-al sex can destroy the sphincter muscles and this can result in incontinence
Sorry guys for being gross but can help it as thats the only way to present some logical answers

For the record I have no problems with gays, lesbians, queers or transgenders as I view all of them as human beings just like others