We priced jobs for a year off a costing for a plant that was never poured, so no line in it had ever been checked against an invoice. Re-costing the same plant at rates we had actually paid came out materially cheaper, and three scopes of work were missing from the model entirely.
An owner sent us both quotations and asked us to explain the gap. Most of it was scope, not margin — and we will not tell him the cheap plant must be imported junk.