RPGMemes

That's cool if you don't overdo it.

In the end it boils down to trust. The party will (most likely) regularly expose themselves to mortal danger. They need to be able to trust each other with their lives. If a character habitually cheats them out of loot they might find it hard to trust that character. So why would they travel with this person?

This doesn't rule out playing an untrustworthy character but it makes it harder to justify their presence, especially over long periods of time. A dodgy thief might be needed for one quest but why are they kept around afterwards? Inquiring minds want to know.

It's a sliding scale. Your arcane trickster doesn't sound like she's super far down the scale so she's probably good even if the rest of the party notices. Or maybe she never even hid it in the first place. That also works.