Vias: to tent or not to tent

A question sometimes comes up concerning whether to tent or not tent the vias on a PCB.  Altium by default does not tent the vias.  There are several considerations.  The silkscreen can be visible over the tented vias.  The bare vias can be used as test points and for reworks.  The fanout vias for the BGA pads must be tented, otherwise shorts could happen.  If a via is very close to the SMT pad, it is better to tent otherwise it is harder to solder.  A large via cannot be tented completely.   If only one side is tented, it could trap flux and cleaning fluids. Then there is the subtle question about outgassing: a tented via might outgas.