Lets start by saying that regardless of which method used to add bleed (because the customer did not do it correctly to begin with) that it is expected that the job be cut correctly. If the cut happens 'exactly' (or pretty darn close to it) then in the final trimmed product the consumer would never have any idea which add bleed methodology was used. Yes, we see it on the sheets and maybe it looks wrong. The real question is how does it look when CUT? If accurately cut, they should not be able to tell.
Ok, ignoring my comments above for a minute, the only remaining option would be to SCALE the content. This can work most of the time but not all. The times it does not work is when there is text content next to the trim / cut areas. If there is text then it could be pushed off the page or into the cut area. A long time ago someone created a preflight to evaluate content within a certain distance from the trim area. Then it would scale one method vs another if I recall. Will see if I can find that old post or workflow for you.
