Most homeowners get three quotes and end up comparing one thing: the number at the bottom. Not because they want to, but because the documents do not give them anything else to compare.
Two of the three will be a paragraph and a price. One might have a line-item list. None of them usually says how many coats go on the trim.
Here is what a scope should actually name, and what it means when it does not.
What a real scope names
Every surface, individually. Not "master bedroom" but walls, ceiling, trim, doors, closet interior. A room is not a surface. The gap between "the bedroom" and the list of surfaces in it is where scope disputes come from, every single time.
The number of coats, per surface. Written down against each one. Not a heading that says two coats over a document that then lists rooms. If the ceiling is getting one coat because it is the same white and in sound condition, that can be the right call, but it should be a decision you agreed to rather than something you discover.
The preparation, as steps. Filling, caulking, sanding, priming, and for an exterior, washing and scraping. These should read as things that will happen, not as an adjective. "Thorough preparation" is not a specification. "Nail holes filled, seams caulked, glossy surfaces sanded, bare wood and patches spot-primed" is.
The exclusions. Everything that is not being painted, named. This is the most useful section of any estimate and it is the one most often absent, which is not an accident. An estimate with an exclusions list is one where somebody has thought about the whole job.
Who is doing the work. Whether it is the person standing in your kitchen or a crew you have not met, and whether the person who wrote the scope will be on site.
What happens if something is found. Rot behind a trim board, wallpaper glue under the paint, a surface that turns out to need a different treatment. Every older house has at least one. The question is whether you find out about it as a conversation or as an invoice.
Three questions that separate the quotes
If you only ask three things, ask these. They account for most of the difference between bids on the same house.
"Is mildew being treated, or pressure washed?" On a shaded elevation those are not the same job. Pressure removes what you can see and leaves what you cannot, and it grows back up through the new coat within a season. Treating it takes an extra step and an extra dry-out. Ask which one you are buying.
"Is the old caulk being cut out, or painted over?" Caulk that has gone hard and split is a gap with a skin on it. Painting over it hides it for one season and does nothing for the sill underneath. Cutting it out and replacing it is slow, unglamorous and the single biggest factor in whether trim lasts five years or fifteen.
"Does the scope say two full coats, and on which surfaces?" Not two coats on the walls. Not two coats where needed. The surfaces listed, and the number of coats each one gets, written down. A painter who is doing one coat somewhere should say so on the estimate rather than leave it to the day. This phrase does more work than any other on an estimate and it is worth making somebody say it out loud. There is a longer version of why in what two coats actually means.
Why the low bid is low
It is almost never the paint. Material is a small share of a repaint and the difference between a good product and a very good one does not move a quote much.
It is labor, and specifically it is the labor you cannot see when the crew leaves.
The second coat. The largest single line that can be removed without the room looking wrong on the day. This is the most common omission and the most consequential.
The drying and curing time. Waiting for a washed house to dry through, or for a first coat to cure before the second, is a day where nobody is producing anything. A tight bid is often a bid that has priced the job without those days in it, which means they will not happen.
The awkward areas. Soffits, the back edges of trim, the top of horizontal boards, closet interiors, the inside edges of doors, the elevation facing away from the street. All invisible from the driveway, all where failures start.
Surface repair. Cracked drywall seams taped properly rather than skimmed. Plaster cracks opened out and filled. Damaged exterior wood dealt with before it is painted. A bid that has not looked for these has not priced them, and they do not stop existing.
None of that makes a low bid dishonest. Sometimes it is a genuinely smaller job because the surfaces are sound. But if three bids on the same house differ substantially, the difference is in that list, and it is worth asking which item it is.
The other things worth having in writing
A payment schedule tied to progress, rather than a large sum before anything happens.
A warranty, in writing, before the work starts — not mentioned on the phone. Ask what it covers, ask what it excludes, and be more suspicious of one that appears to cover everything than of one with a clear boundary. A warranty that excludes nothing has not been thought about.
Proof of insurance, current, in the contractor's name.
A start and finish window, with what happens to it if weather intervenes. On an exterior in this climate, a schedule with no weather contingency is a schedule that will force a bad decision in week two.
The uncomfortable part
The bid that has priced all of this properly is going to be higher, and it is going to look worse on paper next to one that has not, because the document will not make the difference visible unless somebody writes it down.
That is genuinely the problem with this trade. The work that determines whether a paint job lasts is almost entirely work you cannot inspect after the fact, done in the days before any color goes on, by people you are not watching.
Which is why the only real answer is to make the scope specific enough that "done properly" and "done quickly" stop looking the same on a page. Ask for the surfaces. Ask for the coats per surface. Ask for the exclusions.
Ours is written out step by step on the process page, including the reason for each one, and what we stand behind is on the warranty page. Read both before you decide, and read the other two quotes against them.