De nada.
The same thing applies to the extractor recess. Fouling can get carried inside on excess liquids from underneath (slot next to pick up rail on bottom of slide), and from next to the hook and on the side of the slide (all around the extractor). Avoiding using excessively wet brushes and patches helps prevent liquid carrying fouling into the tight places where it can't easily run out. The 9/.40 slides have that bottom cut, but not the .45's.
I've used a compressor nozzle, located under the slot on the bottom of the slide, to direct air up throughout the extractor recess, where I'd see black goo blown out around the side of the extractor. Using automotive aerosols, like brake cleaners, can create condensation inside those tight places, which may lend itself to rust where it can't be seen.
As far as powders? Well, if a powder, or melted lead deposits, form on the breech face, I'd not use excessively wetter brushes to scrub it off, which could let the liquid carry the fouling intro the firing pin hole or behind the extractor hook. Dry brushes work fine clearing it away. Very lightly dampened patches can accomplish good cleaning without losing excess liquid all over the place, too.
Ironically, it's generally been the most enthusiastic cleaning practices that have cooped up the slides and frames in duty pistols, not the neglectful folks who barely ran a cursory patch, brush or snake through their guns. Now, lack of lube after their token cleanings could cause them some issues.
