Safeties and shells ejecting across your field of vision are or can be annoying. If it's a shotgun with cast off for right handed shooters it can affect your shooting poorly and cause you to make poor adjustments to your gun mount, feel excess recoil, and cause face slap..
But there is one issue that causes me to never ever shoot a right handed semi-auto shotgun - it's all the other crap that comes out of the ejection port in your face. It's not just smoke - burnt powder particles and gas are part of the crap, and God forbid you ever have even a minor malfunction like a pierced primer. Not only is all that gas unhealthy to breathe, it can cause eye damage - long term. I have a pair of sunglasses with plastic lenses that show little tiny pin-hole size burns from one round of sporting clays using a borrowed Remington 1100.
I don't even shoot SAs because of that. My doubles, both O/U and SxS all have stocks that are cast on for left
handed shooters. My repeaters are pumps - Ithaca Model 37s - that eject out the bottom. They both have LH safeties. I would, and have, shot right handed pumps with no issues simply because the bolt is locked to the breech until you work the slide. You don't get a face full of gas and other crap like with a SA.