F1 Testing - Dust Sensor?????

It's not dust-proof, but I have a higher tolerance for cleaning a handful of spots off and consider that less costly or risky than excessive abrasive cleanings. Generally though, with the mentioned practices I have very few spots to worry about and when I do get some gunk on there it's still not as bad as cleaning up film scans used to be.

I'll clean it with swabs and fluid if you bring it to Brands! All for the price of breakfast

When I say greasy crap I mean small specks that look like dust until you blow them then they spread out in a line over the sensor. My guess is it is greasy bits of dust, or tiny airborne specks of water along with contaminants. I do change lenses quicky, but I do it with the body facing upwards, so maybe I should start doing it the other way and see if that helps - my guess is that will just transfer the problem to the rear element of the lens, but I suppose that's no worse than having it on the sensor, and actually a bit easier to get to.

In any case, although I tend to be a little anal about crap on the sensor, I try to restrain the urge to clean until the dust is visible in varied scenes at usual shooting apertures. I've only been wet cleaning a little while, but I'd guess I end up doing it about once a month. A static charge brush & blower takes care of minor dust in the meantime.