I mean, think about water fountains. Kids slobbering all over the spout and then letting water pour from their mouth all over the spigot from which you will later drink from.
Bidets are the same nonsense. Water shoots up your bidness, then falls down, getting all over tarnation, and the next time you use it, water shoots up from the same spout that bum-bum juice has just leaked down upon.
Water fountains are one of the grossest things I know. But imagine someone hanging their ass over one to clean it, and then
Oh, and this guy? I really, really, REALLY can't.
PSA: Never use a bidet unless you don't mind someone else's bum-bum germs all up in your crack.