Firstly, here's how you report an ad you feel is inappropriate:www.sparkpeople.com/resource/motivation_ar
Secondly, Spark don't preview, select, or pre-approve their ads.
They use an ad service and don't get to see the ads first. But they can remove anything that's inappropriate - so report it if you feel it so.
Lastly - your web ads are personally customised to yourself and your own browsing history. If you see more naked women, it's because you have been searching, reading, or talking about those types of products, whatever products are using those ads. Eg if they're for underwear, perhaps you've been searching for underwear sellers online recently?
Web ad services customise the ads per person based on your own browsing history.
Deb, in New Zealand