On Eugenics

My girlfriend and I talk about genocide a bit. Normally a variation of "man, people are annoying, we should just kill them all." We're a fun couple. So, let me just post this to cover my arse. I don't really endorse the murder of every retard on the planet. Similarly, we tackle eugenics in a lighthearted fashion, but the common sense impaired may not see why we aren't being serious. Here is, broken into logical steps, the reason why I think eugenics is bad:
1) In order to genetically improve the species, you'd need people with very different positive genetic traits to procreate. Stuff like a smart lady with a handsome man, or a particularly strong man with a creative lady... and these can't be skills that you work for, I'm talking natural talents. And you can't be mating with people with the same traits, no doubly artsy couples. Also, you'd kinda have to hope that the two of you don't share a recessive gene that is detrimental.
2) Assuming such a thing as optimal couples exist, there's no certainty that the optimum traits will be passed on; it's completely possible for smart parents to have dumb kids, handsome parents to have ugly kids, straight parents to have gay kids, and so on. Realistically, there's no way you could pick the right people to make the best kids without a percentage of kids produced being, shall we say, less than satisfactory. And that's not even factoring in genetic defects like Downs Syndrome.
3) So, hypothetically, assume you could develop a system wherein you could identify the two people who, when paired, would make the best kids. Do you enforce them to breed? What about people with which there is no optimum pairing? Considering how easy it is to accidentally sire a little bastard, if you wanted any degree of control over the way the species is drifting genetically, you'd have to outlaw any sex except that which is allowed by this new Bureau of Baby-Making. Which I can see going down so well.
4) So, the alternative would be to try and get a meme going where you only want to have kids with people who are going to produce the best offspring. "Smart chicks, only pork handsome guys!" and similar billboards. Which is retarded in and of itself, and I shouldn't have to explain why. Factor in the Dunning-Kruger Effect (the psychological confirmation bias that causes unskilled people to think they're skilled, and skilled people to think they're unskilled) and it's practically impossible for people to accurately identify which traits they have and which they should breed with.
5) This is all concerning the conception of the children, it says nothing of raising the kids or the quality of the relationship that the kids will be brought up in.
So there you have it, my logical breakdown of why I don't think population control works. I didn't throw in any emotional stuff, you know, "you can't do that to people, think of their human rights!" because frankly, who else but me gives a shit what my morals are?