There is no one search engine in OpenBazaar, that's the beauty of it. Anyone can run a search service returning results that people can see in the client themselves.

Our company (OB1) runs one service, and we do censor those listings and allow people to report illegal or offensive listings. However there are other search engines that choose to censor lightly or not at all, and everyone is free to use whichever search providers (or a combination) that they want.