So... that spiderman shirt... (new job tease)

[Zojha]

Can someone explain why they look at her and see Dancer?

Because she looks like one? IRL, martial arts and dancing are quite supplementary disciplines, as both require physical fitness and control. Heck, some martial arts even evolved from dances and vice versa.

The main hallmarks of a dancer in Final Fantasy are: Status effects, revealing clothing and low stats. The rest differs per game. It's fairly easy to see it as one if you want to see it as one.
And, to bridge the gap to the topic at hand, the spiderman T-shirt also allows people to easily interpret whatever they want into it.

Note: That is an explanation, not a justification. I personally am pretty sure it's meant to be a monk, but Yoshi said "Please speculate", so /huh.