The only way for it to go wrong is if you turn it on while standing over it looking directly into the nozzle. You couldn’t get the room or yourself wet without really trying.

The water is clean because it comes from the water that fills the toilet, not the water that drains from it. Nothing from other people ends up on the appliance or you. Clean water sprays from the device, onto the user, then draining into the toilet bowl. Bidets are much cleaner than toilet seats.