how do incels calculate a womans sex life?

I see incels saying a woman saying a woman is a 7 with a sex life of a 6 saying she had sex with 40 guys for example (and this is a lie, women dont know how to count). Do you incels have a census on the number of people a woman has been with? Like a Dunning Krueger effect or something. what makes you incels think you have the right to do this?