As long as you apply for a visa that does not require for her to declare that she has been refused a visa in another country, she should not have any problems
As far as I remember, visitor visa sub class 600 application form does not ask for this information
However, you may have to give a convincing answer on the circumstances under which she was refused the UK visa, wherever this information has to be disclosed
It certainly reduces the chance of being granted a visa to be honest in any country in the future.
Every CO will treat her application suspiciously
If the reason for which you are fearing that she will be refused are not confidential and you don't mind sharing, then maybe the members can give you a better response
Cheers