They are undoubtably bad for you especially if they have nicotine in the “juice” which most do – they are after-all a form of nicotine replacement therapy. Inhaling steam is not normal and is bound to have some detrimental effect, but the level of harm is tiny. The harm is from Nicotine which is a poison – you can’t get away from this if you want to ingest nicotine in some form (which addicts do) the level of harm is likely similar to the level of harm from wearing a nicotine patch or chewing nicotine gum.
Overall the level of harm is massively smaller than actual smoking and as with real smoking, vaping effects are massively smaller on passive inhalers than active inhalers.
I sincerely expect traffic pollution to pose a higher risk (thats not to say its unpleasant)
As a smoker who swapped to vaping completely for a year and now gone back, the most irritating thing I found about vaping was the way people are evangelical about it, and doing things like deliberately being obnoxious as some kind of rebellion against sensible anti smoking legislation. A perfect example of this is the obsession with blowing big clouds – its done for looks not for delivery of nicotine.