The parts of Africa that BP's come from have between 50% - 80% humidity year round. As long as the cage isn't accumulating condensation on the inner walls and you aren't having issues with mold/mildew growth you should be fine
a little fog or moisture on the sides or glass isnt all bad. it will reach a certain point where its just plain wet on the sides and thats when you need to worry. when its like that for extended periods of time the humidity is around 90 or above and thats just too much. lengthy exposure to those kinds of levels makes everything wet and snakes are very much susceptible to skin rot and ri among other things. as long as you keep the levels around 60-80, you'll be alright.
What is a good way to lower the himidity then. My hygrometer says in the 90's for both of myanimal plastics cages. My larger enclosure has a large water bowl not touching the heat cable but my smaller enclosure has her water bowl on a small part of the heat cable. How can I lower the humidity?
You can open the doors up for a little while to let the cage air out some. As long as you don't mist the cage it should dry out some over the next few days without you doing anything.
i agree with the merchant, it should gradually come back down as it dries out. just make sure you dont mist it, and the level should reduce. when it does you keep it at that level you need.