One easy-to-observe symptom of bad engineering is the haste in releasing key orders early on in the project. Typically, the decision to do a project may take months or even years; however, as soon as a project is approved, this sense of getting delayed every day, becomes a convenient excuse for total neglect of the engineering required.
Much later, it is observed that the project budget and timeline won't be met, and typically get doubled vs the original plan. Bad engineering ends up with double the cost, double the timeline and half the possible quality. Is the hurry early on, and the neglect of engineering, really worth it?
On the other hand, with good engineering, we may see purchase orders being released in a calm and staggered manner. However, such an approach does achieve the project objectives of quality, cost, and timeline. It allows for a good foundation on which several pillars of good factory operations can stand upon, e.g., lean design, traceability, and process capability.
With bad engineering, even though you may order the key equipment to the best and most costly suppliers, as the saying goes, the weakest link in the chain defines the strength of the chain, and likewise you will end up with a factory whose quality is defined by the scope neglected.
However, with good engineering, your investment is balanced across the value chain, spent in the most optimal manner, and will give you the best possible outcome possible from your investment.