Welcome to WebmasterWorld [webmasterworld.com] stimpo!
Most people find that if they are reasonably relevant (come on, be honest now), between their keyword/adtext/landing page, splitting things up, writing new ads and reloading should help.
Good Luck!
Say goodbye to adWords or change your doman..change the site structure and try to bring in more relevancy ( as defined by google).
So in short..change the domain and start making changes which may or may not work during next QS update. The algo keeps changing every few moths. so this is now a game of uncertainity.
Three of my domains seem to escape the QS hit every time.. but two of them keep getting hit every few months. Haven't figured out yet why.. as the sites are all very similar..