I've seen a video of her somewhere dancing. she's better than this. 
There are so many forms of dancing that even if a person is good in one or two forms, it doesn't make them good in all. Ballroom dancing is a dance type that people with a jazz or ballet background could possibly find easy to crossover to but not people with hiphop, break dancing, or even tap dancing skills.
From the video I surmised that the lack of skills was more on Jimmy Olsen's part than Chloe's because all the walking parts were stiff ... stiff armed, stiff legged, stiff backed. The movement lacked sensuality, which is what the tango is all about. Even the part where he put his hand at the back of her head looked unnatural. There is a movement like that in tango, but it should not have looked too -- limiting.
The part I found hilarious was the "freestyle" part where they would walk around each other like dogs sniffing each others tails. Chloe's flirting with her skirts was cute.
Sadly, the lunges and flairs didn't work to show her off properly. *pout*
I miss ballroom dancing. Sigh.
