My 50D's sensor has been dirty for many months. I've been unable to clean it myself and unwilling to let others clean it for me, mostly because I think they either won't do a good job of it or it'll cost me lots of money. I undertook yet another attempt today at removing the specks of dust (and even a very tiny hair!) from my sensor.
And this time I succeeded! Well, mostly. I tried everything: those cotton ear stick thingies, cleaning fluid, hairy blowers, kitchen paper, my own powerful breath. Basically everything that you're never supposed to do to your sensor, ever, I did. And every method just made things worse. Except one.
Using the tiny little blower without the hairy appendage successfully cleaned my sensor! Well, mostly. There's still 1 or 2 very tiny spots in a corner that can be spotted at very high apertures, but I'm leaving them. Every time I blow air onto that sensor it's really just a gamble to see how the dust particles will arrange themselves. I got on a lucky streak and they're mostly gone, but I'd hardly call it a well-designed technique.