I don't think right or left matters, at least not in the cities we've lived in. There may be regional "conventions", for want of a better word, though. If you are really worried, I'd ask around locally. Personally, it's not something that bothers me - or ds.
DS first pierced his ears when he was 8. I couldn't very well say no when he asked, since his younger sister had hers done a year or two earlier.
We talked about it over a period of time (a few months) to make sure he really wanted to do it. We talked about teasing. I explained that some people think that pierced ears in men/boys are a signal or a sign. We also talked a lot about hygiene and safety. He played sports and participated in martial arts, so it was an issue.
His response to the teasing and symbolism issues were that we always told him to think and decide things for himself, and to dress the way he wanted to, and not to pay attention to other people's opinions. Again, I couldn't very well say no at that point, or else I'd be a pretty big hypocrite.
He's 17 y.o. now. It's never been a problem, but we've always lived in fairly diverse, metropolitan areas.