My only true answer for that is that I try really hard to take into account that these guys are REAL people, not just characters I made up. So I can pull from their real personalities, histories, song lyrics, videos, interviews, etc... and use that to my advantage to try to create something that feels as real as it could get. :) I do my very best to try to make sure certain things sound the way real people would speak and act, especially in certain situations. (That, I kind of credit taking psychology and sociology courses for, because it gave me a better understanding of how people work.) I read, re-read and then do it three or four more times to make sure it's as good as it's going to get before I'm comfortable posting these things. :)
And it amazes me and makes me feel absolutely awesome when someone like you comes along and picks up on something I tried so hard to get perfectly right. <3