All the time. If from moving from a fruit to a different fruit, or you know, something similar. I have never had to much of a problem. One thing I do is I only put a small bit of the new flave in, mix and roll,then
vape that down to flush the old flave out. Then I fill up with the new one. Sometimes it makes for a very good new discovery. I had a real tart fruit punch and a real bland cotton candy. together it was better!