1. One size doesn't fit all. As with all things kink (or human, for that matter), slavery is a highly individual proposition. Slavery goes from service in a single scene to a lifetime 24/7 commitment, or anything in between. Some refer to themselves as “this slave” and write their title and name in lowercase. Some would not readily be identifiable as a slave except during interactions with their Master or Mistress. Some are micromanaged and need permission to use the restroom; others run households autonomously within broad guidelines. When someone identifies themselves as a “slave,” there's no telling exactly what that means until you get to know them a little better.
2. Kinky slavery isn't what you find in the history books. The healthy, consensual slavery performed by BDSM practitioners has very little in common with the slavery we learn about in school. Consensual slavery does not include oppression of any kind and generally encourages the slave's strengths and personal development. Gorean slavery, based upon the societal structure explored in John Norman's “Gor” science fiction novels, is rarely well-accepted in the BDSM community at large and is sometimes considered misogynistic, but even it adheres to these basic tenets.
3. Kinky slavery isn't what you find in porn mags, either. A typical slave's life is not the western misconception of the geisha lifestyle, filled with pampered leisure and study of the art of pleasure while breathlessly awaiting sexual service. A typical slave's life is also not the Cinderella trope of dirty work under the supervision of a demeaning, abusive dominant. It's simultaneously a lot cooler and harder!
4. Slaves aren't superheroes (although they'd like to be). Most slaves I know are either employed full-time or work well over 40 hours a week managing their household. They have disagreements, aren't always in the mood for sex, sometimes need to be relieved of duties due to illness or a bad day, and don't have lives any easier than anyone else. Any owner worth their salt knows all of this and adapts accordingly, even if a little “slave magic” escapes their conscious attention from time to time—if your owner thinks the toilet cleans itself, that can feel like a little victory rather than a slight.
5. So what does the slave get out of it? Now that you've let me get on my soapbox about what slavery isn't, let's talk about what it is. Slavery is a total power exchange: a willing transfer of power over one's life to a trusted, committed dominant. In the best situations, slaves can rest easy in the knowledge that their owner will make the big decisions: whether they should return to school, take a certain job, work on physical or mental improvements, or otherwise determine the slave's path through life. And by “rest easy” I mean “work their ass off” —the only other place people are typically made to “be all that they can be” is the Army, and that's not an easy life either!