Help! Viewing potential builders previous work today, what to ask?

[Bonnefoi]

Totally out of my depth with this. We're visiting two former customers of the builder we want to use for a big renovation project, today. All good, then I realised i don't have a clue what I should be asking these very obliging people. Don't want to waste the opportunity but also don't want to ask stupid questions and look like a clueless muppet . Any pearls of wisdom thrown my way would be hugely helpful, thanks!

OK, I've not done this but these questions spring to mind:

1. Do they turn up when they say they will?
2. Do they highlight any problems which may mean extra cost over and above your estimate/quote?
3. Are they clean and tidy?
4. Do they ask for money in advance for pay for large items (bathroom/kitchen fittings)?
5. Do they ask for payment in cash?

I'm sure there are loads of others - I'd google your query and see what comes up!

Are they on budget?
Are they on time?
What things have had to be redone/had errors - who paid to rectify if builder error?
Are bills clear and transparent - you can see what you are paying for?
Are they open to different things - ie you want t german shower tray they have never installed - so they say "no, no you want a matki, I like matki" and then only grudgingly fir the one you want "on your head be it, mutter mutter" (bitter emoticon)
How does the builder communicate with them - and does it work?
Are they on budget/are they on time/aretheyonbudget/aretheyontime/aretheyonbudget/aretheyontime.......AND if not - why not and how quickly was it highlighted. What action is being taken to get back on budget/time?

Opps....think I may need some therapy. Or

Thank you. Meeting went well.