Actually, you can avoid getting caught. You just have to take the right precautions. Luckily I was raised by a couple hippies and was able to smoke openly when I lived with them, but all it really takes to not get busted is the right combination of stealth, paranoia and planning. Also, if you don't seem like the stoner type it can be a good disguise. For instance, I was the nerd in high school and people were always shocked to find out I smoked. I was definitely one of the smartest kids in that school, even when I was blazed out of my mind (I got stoned every day right before physics and did better on the state exam than anyone else in the school at the end of the year )