I've never actually used them before, but when you use the Eugenics SMR policies where it says 'if the slave isn't max intelligence/beauty they are sterilised', does it just make all slaves you buy from the Slave Market max intelligence/height/beauty, or does it just roll you pre-sterilised slaves if they aren't max intelligence/height/beauty? I usually aim for nearly max intelligence/beauty slaves (thus why I always pick the Utopian Orphanage and ask them to do stricter admission criteria), but I've never actually imposed those particular policies before.
At most I've only imposed the other ones like 'slave must be healthy' 'slave must not be ugly' slave must not be dumb' kind of policies. Though I note that the Indentured Servant slave market seem to not follow those policies, probably because they're not truly 'full' slaves, since while it can roll Brilliant slaves, it can still roll dumb as brick ones.