See these costumes?
These were our "brazillian" costumes when I was in Amira Mor's company. They were about 10 years old. They were always the last costume of the night for big jobs. (after 4-5 hours of mulitple routines and costume changes). They were so disgusting, we couldn't stand near party goers, for fear that they would smell us.
The worst was when we had to wear them two nights in a row. Sometimes, they would still be wet from the dancer's sweat the night before. And you always got a different costume, so rarely was it ever your own sweat that you were feeling.
So, no. I don't do anything to a costume when I buy it, except spray a little fabreeze. I spray fabreeze after every time I wear them, too.