As mentioned in the FAQ:
What does deletion mean for a post?
Deleted posts are usually not physically deleted (that is, removed from the system); they're just hidden (AKA soft-deleted). This means they won't appear in search results or data dumps, and normal users following links to them will see a 404 (not found) page explaining the cause of deletion. Links to deleted answers will redirect to the question they were on. Links to deleted questions will either show as "voluntarily removed by its author" if the author deleted it, or as "removed from [site] for reasons of moderation" if it was deleted for any other reason.
Moderators, and normal users with >=10k reputation, see all deleted posts that they have links to. Users with less than 10k reputation see their own deleted posts. Moderators are able to undelete any deleted post.
So, posts are not permanently deleted unless we send request to the team or developer.
Now, when post is deleted as spam or rude/offensive, the body of the post is not displayed users having moderator access tool (10k for graduated site and 2k for beta site) by default, rather they have to "see the revision history" to see the content as declared here:
Going forward, deleted answers that have had any spam or offensive flags raised against them, will not show the answer body but the following text:
This answer was marked as spam or offensive and is therefore not shown - you can see the revision history for details
Where "the revision history" links to the answer revision history.
This applies to 10k users; moderators still view the original message.