I just want to let everyone know that PG is extremely poisonous to cats.
I read the actual paper people have been citing. The amounts they were feeding those cats to cause heinz body formation (flaw in red blood cells that leads to organ damage/failure) were insane……on the order of 10% of their protein intake. PG is also in a lot of other things they're exposed to: dish detergent, hand soap, shampoo, people food, etc..
I'm not saying it's 100% safe, but vaping seems like a drop in the bucket compared to what they get from eating out of clean dishes and being petted with clean hands.
That being said, now that I know 100% VG juice works in my vivi nova, I'm switching to 100% VG juices when I'm inside.
As to the actual question………they haven't reacted. I never smoked inside, partially because I didn't want my pets breathing that

. And I haven't noticed any behavioral changes at all except that they know that part of the kitchen is not the place I put the tuna on a plate or mix the meds into the wet dog food (gf's dog had a bout of ........ probably from eating a plant……vet gave him a clean bill of health…it's a broad spectrum antibiotic just in case).
(yes, my cat eats Tuna sometimes……according to my vet, it's actually really good for her)