I think one thing about Aussie domestic cricket is that spinners always struggle, so it's hard to judge the domestic spinners on their stats. Even the best international spinners coming to play Tests struggle. Warne's average for Victoria was in the mid 30s I think, MacGill's for NSW on a turning Sydney pitch was about 30, and those guys are some of the best spinners of recent times. As for tourists, Swann bowled tidily but hardly got great returns, Murali has been owned on his trips to Australia. The last spinner to average under 30 and take more than 10 wickets on a tour of Australia was Upul Chandana in that short 2 Test series in 2004, Anil Kumble managed to get JUST under 30 in 2003/04 and before that you start heading back into the 90s to guys like Saqlain and Mushtaq who did well in short series, but never on subsequent tours. Australia is really a spinners graveyard.