As others have said, posts are deleted for a reason - and it would generally (IMHO) be wrong to post a screen-shot of such a post (but vide infra). Posting a link to a deleted post, though, has less potential negative impact (as only 10K+ users can see it - but even they can't see it without that link).
I once raised an issue on MSO about a deleted post. I didn't post a link in the original question but stated (as a post-script) that, should a moderator feel that it was OK to do so, then I would (in an edit).
What transpired in that case (the post was deleted by SE staff due to a DMCA request) was that a mod (or maybe staff - can't recall offhand) posted an answer to my question with the said link in it, and also included a 'mini' screen-shot of the relevant part of the deleted post (the comment about the DMCA request).
So, I would always await moderator/staff approval before posting either a screen-shot of, or a link to, a deleted post.
I should, perhaps, add some details for clarity! If the post in question was deleted solely for reasons of (low) quality, and a question is being raised on a Meta-site in order (say) to solicit potential undelete votes, then I would generally agree that it's OK to post a link, so that those with sufficient rep can look over it there and then, rather than wait for it to come along in a review queue (if that's how such things work); it may even be appropriate to post a screen-shot, so that lower-rep users can comment on its worthiness for un-deletion. In such cases, seeking or awaiting moderator approval would probably be overkill.