I think that, whatever Cutie Mark you get for whatever talent, it doesn't control your fate. Rarity's spell is gem finding... not dress making. Yet, that's what she does for a living, and what she enjoys. She found a way to incorporate her special talent into her job, into doing something she loved. Just because you're talent in something, doesn't mean that that will be the only path you can follow. You'd think Rarity would be a miner, being good at gem finding, right?
And what about Cheerilee? Her mark is smiling flowers. Like, what does that even mean? I know she explained it in an episode, something about watching her students blossom, but really, marks can have different meanings.
I have heard that too, about people playing OCs that get a talent they don't like. I don't think that's possible. I mean, Rarity didn't even know what her talent was going to be, it was forced on her. But she doesn't hate it. The way Equestria works, your Cutie Mark will match you in some way. I mean, Twilight Sparkle got her mark almost on accident. It wasn't some meaningful revelation like with Rarity, she just used a lot of magic and then she got a weird mark. It wasn't until later in life that she found out what it meant. So that can happen to, where you have a mark but don't know what it means. But I don't think that anypony would ever hate their mark, or get one they didn't like. Equestria is not like Earth, where you might end up in a career you hate or a dead end job. Their world doesn't work like ours.