I was ok with hidden scrollbars at first, and then I started running into websites with scrollable areas that were padded by non scrollable whitespace. Without a scrollbar, there's no indication that the area is even scrollable, unless you're lucky enough to see some partially cut off text. Even then, it's hard to know where the scroll pane begins and the padding ends. Maybe web designers should either stop using seamlessly pad scrollable panes, or indicate scroll ability some other way, but in the meantime I've turned scrollbar visibility back on.