Ok how about defining it as malts that are either not bottled by the owners or where maybe only one expression exists but is not actively marketed. A provisional list of Scottish distilleries:
I realise that this is a long list, but a lot of these are hard to find so a bigger list means that more folk might have some of them. Also I'm perfectly willing to concede that some of these have established a substantial following and could be knocked off a list of obscurity (e.g. Mortlach, Linkwood, Glen Scotia, Benrinnes). Any thoughts?