can USA citizen who are not residing and working in Ireland get Chinese tourist visa in Dublin

I'm afraid not, since China Embassy in Dublin only issue visas to non-Irish passport holders who are residing and working in Ireland.

Probably not...but the actual words used on their website...on ...http://ie.china-embassy.org/eng/Consular/AboutVisa/t112836.htm

It says..... Non-Irish passport holders are supposed to apply for any type of Chinese visa in the Chinese Embassy or Consulate in their home countries, with the exception that one is residing and working in Ireland.

Now, if English is being used correctly and precisely (!!) supposed to means , yes, but there can be exceptions ...so try! Check out travel agents, especially ones run by Chinese, or visit the office. If you have no success, there are 2 options.... go to the UK where you can get a single entry tourist visa. Second, have your visa couriered to the USA and have someone make the application for you there. I have successfully used this approach.