Something I've done in the past as scum that's been effective is, after a scumbuddy receives suspicion early and defends themself well enough to cause people to change their mind, to tunnel them even though most of the town incorrectly think they're town. If I get lynched/vigged at that point, there's basically going to be no chance of the buddy in question being suspected from then on and they can coast to endgame on it. This is different from bussing in that I don't expect the lynch on my buddy to go through; effectively, I'm bussing
myself
so that another scum will gain credibility.
I suspect this strategy doesn't work so well nowadays (especially because it may becomes visible as a tell that seems to work quite consistently for me and should be better-known: if someone is ignoring simple explanations for what is happening in the game and focusing on complex ones instead, they are probably correct and probably scum).