Aircraft: How clean or dirty are they?

I think I'll just stay home, thanks. I'm already on five different medications for heart and lung problems, and I'm not really looking for another excuse to visit the intensive care ward. I'm quite familiar with it already. In fact, the last time I was there, I was helping other patients find supplies they needed while the staff was busy on more urgent matters. And being wired with a Holter Monitor 24/7 and pulling an oxygen cart around with me for a week was quite sufficient to get me in touch with my own mortality. I think I needed that. I think that was God's way of telling me "Nothing's forever, Kid, except Me - and don't you forget it!"

Anyway - some kid with plastic explosive in his shoe isn't your only worry on an aircraft these days, obviously.