"Muddy point" for Week 5

A fairly basic question this week. I've never worked with Dublin Core, so I'm not sure how far its purview extends. For example, does the metadata by default feed into search engines, if the digital library exists online? Could the cataloger specify that as an option, or is Dublin Core's searchability always limited only to an institution's own network? It seems like it could be especially helpful for a commercial search engine to pick up on Dublin Core's metadata, but I could also understand why search engines might want to avoid metadata that has been pre-programmed by users (for example, to avoid spammers using false metadata as hooks to give their own sites a higher priority).