Are hookas bad for you?

Yes: if you do anything more than look at it, that is. Smoking tobacco or marijuana through a hooka, whether the old fashioned definition (a water pipe) or through the electronic versions (e-cigarettes and similar devices for marijuana), still delivers the drug into the lungs. Old fashioned ones may cool the smoke more, but it's still smoke, with tars etc. E-cigs have unknown issues- no studies.

Yes, Hookah harms: Per the Mayo Clinic: Per Dr. T Hays- " Hookah smoke contains high levels of toxic compounds, including tar, carbon monoxide, heavy metals & cancer-causing chemicals (carcinogens). In fact, hookah smokers are exposed to more carbon monoxide & smoke than are cigarette smokers." REF: https://www.mayoclinic.org/healthy-lifestyle/quit-smoking/expert-answers/hookah/faq-20057920.