From Jeff Robinson at About.com:
n adjective used to describe a noun.
Probably an infinite number of uses. I've used it myself when dialing in guitar sounds. Usually distorted and more often than not narrow in frequency response. Several records I've worked on we actually got some pretty 'skronky' guitar sounds. One that comes to mind is the solo/theme guitar sound on a song called 'Pencils and shades' by the Low & Sweet Orchestra. That came out on Interscope Records and featured actor Dermot Mulroney on various stringed instruments. I've also worked on several projects that had some pretty 'skronky' vocal sounds too. That effect would be achieved in running a normally recorded vocal out through a bullhorn to achieve a more annoying, albeit obvious vocal sound in the mix. One could even record the original vocal with a bullhorn.
Another name for this effect would called 'filtering'. Usually, one chooses a center frequency which will be predominant and then the other frequencies are filtered out or decreased. This creates a spike in the final sound of mostly one frequency. That's about all I can suggest as to my knowledge of it's usage. So often, working in music, finding a common language to describe what you hear and intend is critical. The language becomes nearly as suigeneris as the music itself.
The Gentlemen Callers' sets just kind of blended into on long grind of rythem and skronk.