I can't speak much of PG vapor, other than it dehydrates me horribly, among other effects.
My VG juices, however, seem to have a bit of an expectorant effect on me. Some people report that VG seems to 'make their lungs feel heavy', which could mean that it tends to collect in them, and not readily absorb. I've got little understanding of what happens to it after you inhale it, though.
I don't think that there is much information on the subject, other than anecdotal, and my observations are that when I vape VG liquids heavily, it causes a productive cough occasionally. Not much, when I vape normally.