A few months ago, someone made me notice that I had placed Twilight's cutie mark on one of my vector on the wrong side, so I checked a few other references, and he was right. I had pretty much always used a pre-made cutie marks, adn never really payed attention to its position until his comment; well at least for Twilight. I noticed Rainbow Dash's way before that, but hers is really obvious. Anyway, after his comment I started paying more attention about it. But for some reason it didn't occur to me to check for the other 4. I pretty much assumed they were symetrical.
A week ago, my train of thoughts lead me to this particular comment, and I ended up thinking that they were in fact not symetrical. So I decided to check it. I checked several episodes from the three seasons, and they all match. They're all positionned like in the picture above. Fluttershy and Applejack's are very subtle, but it's still not symetrical. I quickly went through several folders, and a lot of vectors got the cutie marks backward (some of mine included), so hopefully this guide here will prove to be useful.
And related to this, Vinyl Scratch's cutie mark has the bells/balls of the eighth notes facing her tail, resulting in a flipped-from-how-it-normally-is eighth note in her first two appearances on the show.
Just kidding, this is awesome ^^
Who here gets this joke?
Butts.
Yeah, dose flanks