I do not get dust "tits" because emulsion varnishes eliminate these. But sometimes a small clot will show up. I carve this off carefully and put a dot of acrylic paint on it. When dry, I rub flush with micromesh. This is usually after a glaze coat which may have a little more debris in it.
It makes a small distress mark. Does anyone else treat small flaws with "distress marks" ? It seems the obvious thing to do, and also they are at random positions.