Eat with the right, touch anus with the left and always wash hands before you eat. Developed cultures have done this for ages. And they have clean bumholes because they wash instead of only smearing with toilet paper. That shit is disgusting.

Washing can also help against the itchiness. As well as non-synthetic underwear. If those don't help, do indeed see a doctor.

If you need to regularly scratch your anus, you probably have parasites. That's one of the prime ways for some species of parasites (roundworms, I think?, probably tapeworms too?) to spread.

People who think like this don't wash their hands after going to the toilet, so of course it's disgusting for them.

If you need to regularly scratch your anus get a bidet and some ivermectin