As a leftie, I've never had any issues with sewing - at least none that I've noticed. I'm largely self-taught and always sew alone, so chances are, I'm doing lots of stuff in a weird or more difficult way. I've used right-handed scissors for as long as I can remember. And I use the yellow and black Olfa rotary cutter with my left hand, so no problems there.
I wonder if anyone has ever manufactured a "left-handed" sewing machine. I suppose the throat would be on the right side instead of the left. If that existed, I wouldn't even try it. I can learn most things with either my right or left hand, but once I've learned it, it seems nearly impossible to learn it on the other hand. When I try to switch from one hand to the other, I usually just manage to confuse myself.