Lol, you guys can be such dicks. Hey OP, don't worry about these guys, their bark is worse than their bite. Oh and just FYI, if you're asking for advice on stuff like this, I'd post the topic into the Tech Support section, or better yet do a little bit of googling if it's something as simple as how to clean a PCB. Also welcome to the forum, as long as you're willing to contribute around here and put up with what's basically the site's version of hazing for new members you should do fine.
Thanks. I have done some PCB cleaning, but never seen or heard of anything like this before. Before posting I tried looking for "black gunk on PCB" but predictably no relevant hits.