What about hair that is wet and saturated with conditioner? What about temporary colored gels in the hair before you put your hairsticks in?

While I don't see any problem using them with damp hair (except for unfinished black dyed sticks in light hair), I wouldn't risk putting my designs in hair with any sort of chemicals in it, and certainly not any kind of temporary dye that might rub off!  These are definitely two situations in which I'd use cheap plastic hairsticks ;)