There are SO MANY talented former agents and Big 5 editors currently offering editorial consulting services to the general public. SO MANY. Off the top of my head and for the sort of books I represent: Geoff Shandler, Adriann Ranta Zurhellen, Emily Murdock Baker, Amanda Moon, Katie Adams, Jonathan Cox, and I am forgetting tons and tons of others. If you want a gut check on what’s commercially off about your manuscript or proposal, ask someone like this.