There are rarely public toilets on the streets. In public facilities, such as in the airports or in the sights, you will always find well-kept toilets, including those for the disabled.
In summer you will find a large number of well-maintained toilets on the beach, among other services. Wheelchair-accessible locations are also available for wheelchair users.
In cafes and restaurants you are expected to eat something there. Especially in the vicinity of sights, people don't like it when the toilets are used without eating or drinking something in the restaurant. But just ask politely, in "emergencies" you will rarely be refused the use of the "little place". If all else fails, simply order an espresso.
While the toilets are always clean in public facilities, you will experience the whole range in gastronomy: from "well" to modern designer places, everything is there. There is certainly a general consensus among the innkeepers that the really bad toilets don't exactly attract guests.