Nothing here is gospel, absolute, concrete, scientific, or in any other way, defining, or a basis of decision making.DASH-8, and they wish to follow the clean aircraft concept to the letter. They land in B.F.N. with an unexpected trace amount of ice on the very front of the leading edge, and no tools available to clean it off. What do they do then? Wait? What if there is nowhere warm to wait, and it's not going to melt on its own until several months later? What do they do when the company is pressuring them to go?
It's a discussion to encourage pilots to think about what they're taught in academics training rooms, then take that out into the real world, where a lot of the things they are taught must be applied as guidelines, or cannot be applied at all. The concept that There's no such thing as a little ice, or even the When In Doubt theory (i.e. you first have to find there IS doubt, then ponder the ramifications) is drilled into us year after year so that non-thinking automatons will conclude a plane cannot fly with a little ice on it - and will subsequently fall out of the sky, crash, and everyone will be killed - is what they are aiming for.
I encourage you to consider what the statement means, then try to rationalize that in a real-world situation.
I am "living" testament that there IS such a thing as a little ice. But where the boundary is between a little and a more than a little cannot be defined scientifically.
i.e. there are no concrete non-self-incriminating answers to your questions.