When I enter a new post title like "My Latest Greatest Idea" the slug becomes 'my-latest-greatest-idea' and I type in my content, post it, and all is well.
7 months pass and I get another idea.
I then start to enter a new post entitled "My Latest Greatest Idea" and the slug becomes 'my-latest-greatest-idea-2' and I type in my content and post it.
I'd like the permalink area on the screen to turn red or orange or something to tell me that a duplicate title was detected and a -2 wart is being added.
Perhaps a note on the screen box says "Note: Another post has a similar title and the permalink was adjusted. <link>View the other post here</link>."
"Even if I trash the first post, I can't get the -2 to go away."
Our users find it frustrating when they see the -2 or -3 or -4 show up on their URLs and they can't figure out why. We hunt down the issue and it turns out the original permalink is on a post in their trash. Emptying their trash allows them to get a clean slug on the permalink.
Providing the informational box above will help alleviate this issue.
Coding this should be somewhat trivial. 1) Find the code where the duplicate slug is detected, 2) use that post info to assemble the cautionary note, 3) update the UI css and content with that note.