DH grew up attending a private school that taught both a left-to-right and a right-to-left language (and I'm starting to learn the right-to-left to stay a step ahead of our offspring!
) so I asked him.
He said that it wasn't a big deal either way. Most kids were right-handed, and it was known that it was easier to write towards your dominant side, but it really didn't get any attention. He'd also never heard or thought of left-handed scissors.
That said, he's mostly right-handed. He says both languages look fine in his right hand, but the right-to-left language looks a lot better than his left-to-right when written with his left hand.
As an aside, Dan Pink's book A Whole New Mind has some fascinating right-brain/left-brain stuff in it, including how your brain processes information viewed from L=>R versus L<=R and how it impacts the languages written those ways. It explains (I'm oversimplifying), for example, why English spells out its short vowels but Arabic mostly writes consonants and long vowels and leaves the short vowels to be interpreted contextually.