Someone that points at your home(bathroom, roof, gutters), and goes into what will happen as if they have seen it before. That means they've gotten their hands dirty - and know what their crew will do and does a good job explaining to YOU, which means they will do a good job at explaining it to their crew. 

If they can't answer this with confidence, they are likely a sales guy the company hired that hasn't ever picked up a tool and can't explain things well, because they haven't been around it long enough. 

Good contractors do business with good customers—the kind of homeowners who understand that a company (and its team) needs to make a fair profit to stay in business and deserve to do so. 

So even if they say "not much, not much as I should, or even provide a number like "a couple thousand" You will know and you will feel grateful for paying them for a job well done. 

If a contractor gets defensive, dodges the question, or tries to hide their numbers, even worse, gets flustered and reacts with a bad attitude - just respond" I was just wondering - to make sure you were going to make enough on it to do a good job" this will  defuse the interaction then tell them you will call them. 

If they can’t be upfront about a simple financial question on day one, how are they going to handle communication when something goes wrong halfway through the project? A pro who is confident in the value they provide will have zero issue explaining their margins.

Honesty. They don't need to tell you their entire life story - but they should give you a breakdown of where they come from and what lead them to you. Small Talk. 

Honesty, because you looking for how they react to situations. Things will go wrong: material late for delivery, worker called out sick, it rained, the tools got messed up somehow, etc. Home Depot was out of what was needed to finish the job,

It happens all the time. How they prepare and react to it, is what matters. 

This is when you will hear all the work that goes into it. They should tell you everything you will need to do it and it explains their value to you. Anything short of a walkthrough - means they weren't really listening to you to begin with.