Does the robots.txt Disallow line really prevent nodes being seen?

Our CCK content type we use to record our volunteer hours is Unpublished by default. My reason is that I do not need those individual nodes published for the world to view. I use Views to display the results in a Table format for the individual volunteer and the volunteer coordinators.

I recently added the Taxonomy Other module. It requires the node be published for the New Term to be added to the Vocabulary.

Is the only solution to publish all those nodes and add a Disallow line to the robots.txt file for that URL path? I had read that the search engines may still scan those files.

Ashford