Citrus/fruity liquids are abrasive to cheap plastic. They are abrasive even in their natural form. Example: Lemon is often used as a cleaning material, as is orange. Some people use those types of cleaners because they are considered "Safer" than traditional chemical cleaners.
Orange juice can hurt your stomach and give you heart burn. But people still drink it. Thug Juice is a grape/watermelon/menthol blend and is not citrusy, but since it is a fruit and may be acidic, that is likely why it cracked your tank. Thug Juice also happens to be a favorite of mine. I like it in my ProTank at 2.2ohms and 4.1 volts.
It is a good bet that the safest thing to do is no vaping at all. However, to judge the safety of particular juices that crack plastic is not a good argument. I would be more concerned about the safety of the plastic rather than the juice.
In fact, if your plastic tank cracks, be sure to throw it out right away. Plastic is 100% man made and uses lots of chemicals to create it. Vaping juice out of one that has cracked through cannot be safe for anyone.
