Why does nobody know about Dirty IF, what is your preferred window

Either you are all clean fasters or making it up as you go along. I have been IF for 4 years and even do 5:2 occasionally. I posted to see if anyone else does dirty fasting. But maybe nobody knows much about IF really. I tried clean fasting but find it too hard. So just wanted to ask other IFs if they do occasionally try flavoured water or add cream/milk in tea or coffee. Does it really help if you keep it going. 

Which is your preferred window, 16:8 18:6 or even 20:4.