There is always going to be a small chance that every single toffee is het albino also, so pick a number, how many eggs do you want to see until it is "fact"? For most of us, there is enough evidence from the breedings already done. Nothing is ever going to be 100% fact so you have to make an assumption at some point.
As I said in the other thread, Albino and Lav do not lay on the same locus. So toffee has to lay on one or the other, there is no in between, its just simply not possible, or you guys have a new theory on how DNA is built?