Maybe someone will come across this one. But I had an issue with screen and tmux making themes in vim ugly and hard to work with (and i wouldnt doubt if dtach and byobu cause the same minor head ache). By hard to work with, I mean some of the colors were blending in with other colors so it was hard to see anything.

The solution? Well if your using Putty, change your putty colors to something like this:

http://www.infotinks.com/kittyputty-desert-theme-easy-on-eyes-and-much-more-beautiful/