18K image 50D.
I knew it was dirty but never shooting a bland sky at F22 I never really noticed until a few months ago. I decided to get a sensorklear pen and give it a go cleaning after blowing a big chunk of crap on it a couple of months ago with a blower from a cleaning kit. You can see the chunks it left at the bottom left, 3 big pieces close together. Those spots and a couple others were actually showing up at normal open aperture settings, so I knew I had to get rid of it ASAP.
Well, the pen finally showed up today after a long delay, so out for a current pre clean sample photo to show what I was up against.......scary! Sorry about the tree in the first shot btw!
Anyhow, It took quite a few attempts to get it to where I am happy enough with it. Shoot/clean/upload to PC/look, and repeat....... I seemed to be doing a bit of spot "moving" as opposed to REmoving. I'd sort out one annoying spot, then I'd find a different one on the other side for example.
Finally I came up with what you see in image 2. I can still see a couple of spots which are on the sensor as (it's the same two spots on 2 different lenses), but I'm not going to worry about them for the time being, I think you will agree it's like night and day!
To be honest, all this gunk on my sensor and it was only one or two I actually ever saw in 99% of photos, but I feel better knowing it's clean LOL! (j/k) .......or near enough to clean anyway 
oh, so much for auto sensor clean, may as well turn it off I reckon 
oh and to those who are scared to clean theirs, just do it, it's no biggie






