What I think a big thing is towards having a nice rooster, is spending time with them. I mean I don't know what else to attribute it to, but we try to spend a few minutes of every day just socializing with all the birds in our flock, talking to them, admiring them, bringing treats, handling them. We don't do it as much in the winter, of course, but we do in the summer, usually a lot b/c we are outside more. We have, or have had, roos of all different ages and breeds, and we have only had one who was aggressive (he challenged a skunk once and paid the ultimate price) and one who bit when he was young. Whenever he would bite i would pick him up and pet him. He is two years old now and one of the tamest, nicest, friendliest roosters we have. But they are all friendly. We don't have a mean one in the bunch, and we have a few. I think people who have problems with mean ones are intimidated by them, and instead of addressing the problem they avoid it, which just makes things worse. At least, I think that's true in a lot of cases.