In my opinion a toilet seat that has not been cleaned is more dirty than a phone is.
Think about it with a toilet seat butts are sitting on it and poop can sometimes get on a toilet seat as well as urine from a number of people if it's a public toilet.
Your home toilet seat is likely cleaner than a public toilet seat is though but your phone although dirty is likely cleaner than any toilet seat will ever be.
I always wipe my phone down every few days using baby wipes which helps to keep the phone clean and if I have the flu or cold etc then I will use some Clorox wipes to help clean the phone to kill germs.
But your phone is likely cleaner than a toilet seat or even the money you touch.
Money is passed from person to person and likely has been down someone's pants or bra etc while your phone has only been likely in your possession.
So if you keep your phone wiped down with wipes or even a damp cloth with soap you can keep your phone cleaner than any toilet seat.