Most homeowners evaluate contractors on two things: price and the impression they made in conversation. Price is relevant but often misleading without a common scope to compare against. And the impression a contractor makes in conversation tells you something about how they handle new clients, but not necessarily how they handle problems once work is underway.
The contractors who cause the most difficulty are often the ones who make the best first impression — they understand what clients want to hear, and they're skilled at providing it. This isn't cynicism; it's just a pattern that comes up often enough to be worth naming.
Questions worth asking
The most useful questions are the ones that require specific answers rather than general reassurances. "Have you done similar work before?" is not useful. "Can you show me a project of similar scope that you completed in the last two years, and can I speak to the homeowner?" is useful.
A few others that tend to produce informative answers:
"What's the thing most likely to add cost to this project after we start?" A contractor who says "nothing" either hasn't done projects like this or isn't being straight with you. A contractor who can give you a specific and plausible answer is showing that they've thought about the work rather than just the sale.
"How do you handle a situation where work can't proceed because a previous trade hasn't finished?" This is about schedule and dependencies. The answer tells you whether they think about sequencing at all.
"What's included in your quote for materials?" Specifically: are they sourcing materials and billing them through, or are you expected to supply certain items? If they're sourcing them, what's their margin? Some contractors are explicit about this; many aren't.
What the quote format reveals
A quote that's a single line or a summary total tells you the contractor hasn't broken the work down in enough detail to quote it properly — or prefers not to. This creates ambiguity that's structurally in their favour: when scope questions arise later, there's no baseline to refer back to.
A quote broken down by trade and element is more useful, even if the totals are similar. It shows the contractor has thought through what's involved, and it gives you something to compare across multiple quotes.
The format also tells you something about how the contractor communicates. If the quote is clear and specific, that's evidence of how they'll communicate during the project. If it's vague and hard to interpret, that's also evidence.
Things that don't matter as much as they seem
How quickly they respond to your initial enquiry. There's a belief that fast response time signals professionalism, but it often just signals that the contractor is hungry for work right now, which can mean they're less busy for a reason, or it can mean nothing at all.
How tidy their vehicle is, how they dress, whether they have branded workwear. These are marketing signals, not craft signals. The correlation between presentation and quality of work is weaker than people assume.
How positive previous homeowners sound. "He was lovely to work with" and "the work was done to a standard I'd hire him again" are different things. Ask specifically about whether the work was completed on time and on budget, and whether there were disputes.
The limits of evaluation before work starts
There's a limit to what you can know about a contractor before you've seen them work. References help. A site visit to an active project helps more. A small initial piece of work — if the project allows for it — is the most reliable test, but most renovation projects don't have a natural way to structure that.
What you can do is reduce the room for things to go wrong through a clear scope and a payment structure that's tied to milestones rather than a large upfront payment. These don't guarantee a good outcome, but they change the incentives in ways that generally help.