I am a cat lover myself...currently have three living with me. While my cats may POSSIBLY hop up on the kitchen counter when I'm not around...they wouldn't DARE do it when I'm at home (or lets just say "awake")
Cats on a kitchen counter are indeed unsanitary. I would advise that you do everything you can to discourage them. They CAN be trained. If they need an elevated spot to eat (if you have a dog that eats their food, for example) then you can fix them a table or ledge of their own.
A little off-subject, but just had to give my two cents' here. Don't want the general population believing that just because you have CATS in your house, that they are allowed to put their "poopie-feet" on kitchen tables and counters!
P.S. Clorox Cleanup is a good sanitizing product you can use to wipe down your counters BEFORE and AFTER any food preparation.