Tableover, I am inclined to agree with you about many of the postings on this thread (and many of the others) and, in general, about the rush to judgement without the benefit of all the facts. However, of the aircraft that I have flown I do not recall any of them that permitted departure with any form of deposit on the upper wing surface. 'Could be mistaken but I don't think so.
Regarding whether this is a suitable forum in which to raise flight safety issues; I would say that it is a very good forum - look at the responses to the various threads. Not all of the posts have any real relevance but there is a wealth of experience being brought to bear as well. If nothing else it has put this topic in the spotlight and if it is a factor, however small, in avoiding another Potomac incident in the future then well and good. Pick out the good bits on this site and we can all learn something along the way IMO. The AAIB reports are good but lack the immediacy of PPrune and there has to have been a very serious incident or accident before they become available, this site gets the minor incidents, or even non-incidents, out in the open for discussion from time to time, hopefully to our general benefit.