Don't know about other AW owners, but I find it looks pretty good even when mucky. Always seems quite bright. Wash it most weeks if I have time but lately been every other week.
Main problem seems to be tar spots around the wheelarches, and the front and mirrors being plastered with flies and bugs. The Autoglym tar remover and fly shifter is a great help. Guess mine will need a wax soon.
2010 BMW 320d M Sport Business Edition Touring, Alpine White
2006 MX-5 Mk3 2.0i Sport, True Red
2008 BMW 120d M Sport Coupe, Alpine White (gone)
1999 VW Golf Mk3 2.0 Cabriolet, Jazz Blue (gone)
and an Orange P7 mountain bike!