Seems to be a lot more oversolds on flights I have been on in recent years than before, but load factors are up, upgrades are much harder.
Never personally been Voluntold, but I would guess they mostly leave business class, full fare Y and higher tier status alone.
Did see two groups get bumped recently. One a whole family, well three of the four were told. They were still arguing when I boarded. The other a single traveler, he seemed to take it OK.
I used to volunteer a lot as 90%+ of my travel is business, mostly going somewhere to then go overseas, to a location I'm never in a hurry to get to, and I try not to plan meetings the morning after arrival. Rather give up the seat to someone who may really need it, and lets face it, get a few hundred back for personal use. Though they made the later increasingly difficult to use with the carrier I used to carry status on so I'm not longer the first one at the desk offering up my seat.
From a customer perspective I'd be pretty pissed to be seated picking out my next Giant Tiki Head purchase from Skymall magazine and being told to leave, only to see crew coming down the jetbridge to take my seat. Certainly wouldn't be kicking and screaming, but would be calling the Medallion or AAdvantage Executive team about the experience once off.