I'm assuming these are juices that you have never used before? If you are vaping a 50/50 juice and not getting much/any vapor, then there's a real problem with the juice (it's not what it says it is) and I wouldn't vape it any longer. I am very particular about the vendors I deal with when it comes to juice. I actually only deal with 2 vendors and I have been for the last 5 years. Obviously, there are more than 2 good vendors out there when it comes to juice, but I know the 2 I deal with have quality control in hand and one of them has an in-house chemist. I would spend some time researching those with whom you do business and would particularly stay away from mom & pop stores in general. good luck.