tattoos and the work place

Hi all. I'm currently contracting at a business today where I noticed the nice and friendly receptionist's back. Her back had beautifully detailed tattoos (very lacey and butterfly like) went up to her shoulders and she wore a singlet type top to endure her assets were well noticeable to all!

I made a positive comment about her tatts to one of her co-workers and he without hesitation said "yes, and the tattoos were conveniently concealed during her interview, but now she has them on full view now that she's got the job"!

So my question is, is it one's right to conceal tattoos during a job interview and them have them uncovered once employed?
And does an employer have any rights to ask to have the tattoos concealed or sack the employee on the grounds that they were not disclosed at time of employment?

Your thoughts.........