witch are the countries that are considered more relevant in quality traffic ? is italy one of them ?
IMO it is very difficult to say. It depends on website content and which kind of customers/visitors you are looking for.
Completely depends on your website... if it's some kind of Italian niche you probably want Italian traffic...
For "standard" quality traffic I'd say US, UK and India. But it depends on what you want to do, and then the quality traffic is named targeted traffic
you should not look at the countries and they traffic from there. Instead look at your own website and increase traffic by optimizing your site - to the different countries. Traffic by itself is nothing - you need good converting quality traffic.
it's very difficult to say that quality traffic this one or this one, so there is no thumbnail rule that from where we gets the quality traffic?.
I'd say study what the people of Italy are searching for online using the search engines. Then create those specific products that they will readily buy credit card-in-hand. If you've already have an existing website, you can geographically maximize your search engine visiblity in that specific country via Google Webmaster Tools (Settings) and keep testing with Google Analytics until you know exactly what will make them convert from visitors to customers.
I'd probably consider traffic from UK, USA, Canada and EU to be quality. Italy could be considered one, but as the others have said, it really depends on what you're promoting.
It depends on your website niche and which market you are focusing. Generally i will say US, Canada and UK
It will depend on what language the site is in and where the publisher is located. US Publishers generally consider non-US traffic as poorer quality.