The thing is vaping IS smoking in California and most leases have a non smoking and "illegal activity" clause which includes drugs (MJ) obviously. Your defense would be to have a legal card but that won't help you with a non smoking lease. You could get sued for damages evicted or have a nuisance case brought on you by a neighbor.
It really boils down to your landlord and your neighbors. The way you handle your vape clouds is also important but not always realistic. Somebody is going to smell something at some point. All it takes is one A hole to ruin it.
The USA used to be so kick back and now it's a police state run by LIBERALS. It REALLY pisses me off how things are these days.
I go back to California in a few weeks and will look again but the more I research the more I feel living in Cali would be another version of the police state I already live in....but with better weather