Yes, it's a dirty little secret... many of today's pros and IDSF dancers have atrocious posture.

You see it on the standard couples too, if you see them dance out of costume.

So, are you saying that it's okay to have this posture? I personally think it looks good... but I rather do things the correct way.

You need to keep your spine aligned, stomach in and back straight (a strong core) not only for aesthetics but for many other reasons that directly impact your dancing, including balance. While I'm sure there are some dancers that have arched backs b/c of poor posture (just b/c they dance doesn't mean they dance correctly), I'm sure many that you've been looking at only appear that way because of the illusion created from their weight being forward.

Juice23. Dead right. You have obviously been instructed by somebody who knows their trade, a competition dancer.
An arched back is a sway back. If you have access to a Slavik tape he does show that the back must be straight, and demonstrates both, also how to take the arch out of your posture.
Secret. It doesn't look good and is incorrect.

Okay, I see. Thanks a lot for the feedback.
So, just to make sure, what you guys are saying is that the back itself should be straight, but on an angle forward.

Quickstep, where can I find this Slavik tape you speak of? Also, are there any exercises you guys know that will remove the arch out of my posture?
Unfortunately I have a very flexible and arched spine because, when I saw the movie The Matrix for the first time, I would practice imitating the backwards bend that the guy does, and so now I have a natural tendency of arching my back when I'm standing, and my teachers tell me to stop arching my back when doing the smooth dances as well. But hey...at least I can do the matrix move :)

Yes, quickstep I am fortunate to have a very good teacher and I have had the experience of overcoming a slight sway back myself Correct posture and moving from the standing foot give so much power to one's dancing.

For strengthening the core and aligning your spine I recommend pilates, certain types of yoga, and just to be concious of it in your everyday life. If you focus and work on it enough, the correct posture will become habit and muscle memory.

Jiuce23. Do you spend time on Rumba Walks in your studio. where I go there was this couple, that I would try to get up behind and follow on this weekly ritual. Anyway they took off and went to live in the UK about three years ago. The rest of us keep walking. Anyway this couple got to 37th professionaly at the UK Titles and repeated it seven days later coming again 37th This is just last weekend.
Rumba Walks forever in the words of Karen Hardy former World Champion.

lol! And isn't it the truth? Rumba walks are the best for practicing correct latin technique and posture and NEVER get old. Donnie Burns still practice rumba walks for hours each day until he retired.

Now if only I could get my rumba walks to look like Karen Hardy's. . .

Ah, no wonder my rumba walks suck, my posture is bad.

But practicing rumba walks is definitely some hard work....

Dancers are only as good as the amount of hard work they put into their dancing.