Some additional points to throw out here...
-The white cloudiness is, as others have said, dissolved, semi-dissolved rice solids.
-Nigori zakes are inherently unstable since the rice solids are primarily starches, and that can be converted to sugars by the residual amylase enzymes floating around in the brew. Koji molds (Aspergillus spp.) are pretty fussy, and die off early in the ferment due to the presence of alcohol and the lack of oxygen. But the enzymes they've produced remain active for quite some time unless denatured by heat (or some other extra-ordinary measure). So, in nigori-zake the enzymes can turn starch into sugars, which the fermentation yeasts (still viable in rather large numbers) can then ferment. Because of this, the vast majority of nigori-zakes are pasteurized.
-Kasseishu is not bottled while it is actively fermenting. Or at least it's not supposed to be fermenting, since that would be in contravention of some very basic Japanese alcohol production laws. Rather, it has the potential to re-ferment since it is "active" (which is what "kassei" means).
-The term "nama zake" means "unpasterized sake". There's lots of nama-zake available which takes advantage of the same filtration technologies available to wine producers. Nigori-zake can't be sterile filtered, of course, given the cloudiness. So a bottled nama nigori-zake would have great potential for re-fermentation... in general they're quite rare.
-Other nama zakes, even if they're sterile filtered (almost all of them will be if they're being shipped any distance), still need to be refrigerated because the lack of pasteurization renders them very susceptible to temp-induced instabilities after bottling, both chemical and microbial.
-Finally, about Bwood's "glue" smell... three of the sake brewers I talked with scratched their heads over this and then said the same thing, something like: "Lots of glues are starch-based. Given the raw materials, is it possible that the 'glue' smell would more correctly be stated as a 'starch smell'"?
Cheers,
