If the flavors are similar, such as fruit=fruit or coffee=coffee, there shouldn't be any problem. Certain flavors that are unmistakenly strong such as cinnamon, the mints, and menthol might pose a problem.
I agree for the most part.
Certain flavors can stain a carto with that flavor (strong cinnamons, menthols, coffees, and red bulls), so switching flavors to something that blends well with the previous flavor is ideal. For example, switching from a strong coffe to vanilla, or switching from a cinnamon to apple works great because those flavors mix well.
If you're switching from a flavor that does not stain the carto to another flavor that won't mix well I have a short process I like to use.
1) flood the top of the carto with the new flavor.
2) quickly block off the air inlets near the
threads.
3) blow through the top of the carto pushing the new flavor down and the old flavor out.
It's basically reverse priming, and you usually have to do it a few times to get the old flavor out. You lose a little liquid in the process, and it's a little messy, but it's the fastest way I've found to switch flavors quickly.
