Cloudy or dull lustres or metallics may be caused by insufficient ventilation or firing to an excessive temperature.
If overglazes are applied to a textured surface and they fire off the raised areas, but fire perfectly in the recessed areas, this usually indicates an over-application of colour. The weight of the material applied pulled its off and onto the recessed areas.
When firing lustre, do not place the piece to be fired directly on a hot bottom or shelf as the radiation of the heat will drive the lustre away.
It is best not to fire lustres with china paints as the turpentine in the china paints may distort your lustres.
Do you have a green glaze that won't take a gold firing? Try firing it at a higher or lower temperature than your usual gold fire (cones 018-022)
You can apply gold using a pen designed for that purpose.
Ventilation is the key to satisfactory firing of metallics and lustres. The kiln should remain open until all smoke and colour have ceased.
If a piece removed from the kiln that has had gold lustre applied, has hair-line cracks, it has been over-fired.