Recently I posted a query about cheap, fluid potting compound (just for hobby use) as I have been potting repaired electronic modules in neutral cure silicone sealant. I did suggest hot melt glue as a filler. I am awaiting some liquid potting compound but in the meantime soaked a hot melt stick in water for a few days and tested with an insulation tester (when dried). It appeared not to be hygroscopic and was a good insulator. It was only a cheap bunch of non-specific sticks from a K-Mart/Reject Shop outlet.
I view the practice of 'blobbing' components/parts down with hot-melt as for initial prototype only (and lazy bodge-artists.) Maybe I'm an old snob, but screws, washers, brackets and pillars etc are the way to go...
Regards, BT