So it generates bunkers?
What was on Endor was an Imperial Installation. It consisted of the deflector shield generator (that big dish-thing), and the bunker (mostly underground, but connected to the launch platform where the shuttles landed).
Despite what Force Commander indicates, a "garrison" isn't a building, it's the body of troops/vehicles. The building is just the place where they're stored. "Garrison" can also be used as a verb to refer to the place where such and such is stored when not in use
So yes, there were troops garrisonned
on Endor, but they were garrisoned inside the bunker.
If Vader had left a garrison on Bespin, he would've probably shoved the Wing Guards out of their barracks and put his stormtroopers there (the Dark Lord being too cheap to spring for rooms at the Bespin Towers Hotel/Casino).
Either that, or he would have had a drop-ship drop one of the pre-fab garrison buildings into Bespin's atmosphere, which would indeed have been unfortunate.
[ June 29, 2001: Message edited by: BeastMaster ]