Let's say you use the title "Bush's worn out shoes" to refer to what another president would have done if he were in Bush's shoes during 9/11. Does that make any sense, or it is too much of a jump, from an idiom to a random phrase barely related to the idiom? The title is for a news article.
Firstly, I think that the title "Bush's worn out shoes" could be made more clear with a simple adjustment:
"Stepping into Bush's worn out shoes."
Or something similar, adding a verb to clarify. This makes the specific idiom you're going for clearer. When you're playing off an idiom, you have to be straightforward about it, especially since not all of your audience will be native English speakers and they might be confused about why you're writing about the president's shoes.
However, that is something to consider: is a title containing an idiom going to be understandable for non-native English/ESL speakers? Idioms in other languages can be completely lost in translation, especially if your article is going to be translated into other languages or read by people who haven't heard this specific idiom before. How should a translator convey this idea? By using a similar idiom from their own language? What if they don't have one?
This is something to consider. This particular idiom is probably well known enough that it won't be a big deal, but I think it would be good to keep it in mind in future, if you happen to be in a situation where you want to use more obscure idioms.