I have a sneaking suspicion that part of the problem lies my workflow, specifically, with scanning the negs, which is the first thing I do after the film is dried and cut. I do this mostly as a sort of a digital contact sheet, to see if any are half decent. Of course some scans end up on this place. Trouble is, I think, that when I bring the scanned image into my favourite software and hit 'Auto contrast' or whatever they mostly all look fine, when in actual fact the negs can be poor. The software is too good, basically - it can rescue poor negatives far too easily and therein lies the problem.
So...how to proceed. The solution of course is the most obvious - don't scan. Get my feedback from the darkroom. Perhaps then I'll learn better how to produce better negs - ones that are easier to print.