The line items that matter
Tear-off (per layer), underlayment (synthetic? ice shield at eaves/valleys?), drip edge (aluminum, both eaves and rakes), flashing (pipe boots, step flashing at walls), ridge venting, and the shingle itself by name and bundle count. Each line is a substitution opportunity — the quote that says "underlayment" without naming it is pricing the cheapest roll on the shelf.
The year-five substitutions
Felt instead of synthetic, missing ice shield, unflashed valleys, reused pipe boots, no ridge vent. None fail in year one; all fail in years 3–8, and none are visible from the driveway. The itemized quote is your only defense — insist on names and quantities, and the vague quote disqualifies itself.
The three-quote discipline
Get three itemized quotes on the same spec (hand them your square count from the calculators here). The spread runs ±20% on identical roofs; the low outlier is usually low for a reason findable in the line items. The middle quote with named materials and a real crew wins more often than chance suggests.