I had the misfortune of having someone get white over spray on my Mach 1, which I didn't notice for two weeks. The over spray came off the red paint easily enough with a clay bar, but didn't touch the over spray on the black matte. Other than a respray, none of my several contacts had much advice.
While searching online I ran across a spray on product from Dr Beasley's that claimed to remove over spray from matte black. Riiight. I figured I'd waste $35 plus shipping before I'd respray the hood. I had no faith it would work, but I'm a believer in it now. Directions said spray it on, wait 5 minutes, wipe it off. The first application removed most of the white speckles, so I applied a second coat and waited 8ish minutes. The result was effin magic. Well worth the $50 and twenty minutes.