Hi!
Well…
Static Lighting Level Scale: how detailed you want the light to be calculated! The lower you go, the more detail you get! (0.15 for archviz)
Bounce: above 10 you can get strange results
Quality: quality. Start with 4 and only for the final build go for 10 (maybe 8 is also enough) This is the setting that will raise building time the most!!
Smoothness: how much detail should be blurred out! 0.6 will keep the smaller shadow details too!
Environment intensity is why 0?
Compressed lightmaps will cause you “dirty” results!
I think the biggest problem with the scene is lightmap resolution!! …and also the way the scene was built… Overlapping faces will give you light/shadow bleeds!