Do closed questions show up in search engine results, like Google and Bing?
Well, if I run a Google search that I know hits a certain closed question, I'll see the closed question as the top-most result.
This is actually a useful thing for duplicates where there's often some significant terminology choices. The presence of duplicates will expand the radius of search terms people can use to find the one concrete answer we have on the subject. So it's intentional that closed questions show up.
Deleted questions, however, do not, and that one of the two common fates of non-duplicate closed questions (the other fate being reopening). Mostly for this reason, as it were. We don't need people searching and finding the junk we don't want, after all.