That's an excellent way to handle it - and get a true picture of how they will be.
I have always had a similar approach - but starting at initial contact. I find out who they are and about their basic background usually on a video meeting (camera on). I tell them very briefly what the position is (again as they have already read the ad or watched a video or both) and then I ask them if they have any questions about the position.
Next I ask them to tell me about themselves and their experience - and why they want the position I am offering.
Even though it is a common couple of questions - I still like to get their response to what is their greatest strength and what is their greatest weakness.
Once I decide to move forward - then I do my due diligence and that means thorough background investigations on everybody, MVR, and drug test. I also conduct a criminal records check - and check all social media. Whether employers realize it or not - the employer is hugely liable for the conduct of their people. That means potential legal issues if they are NOT checked out and they harm someone.
After all that - they meet for a formal orientation that lasts at least one full day. They are given WRITTEN policies and procedures for which they sign a receipt. These thing are also gone over with them verbally. They are asked if they have any issues with anything that is being asked or required.
Then they go out under instruction as a Trainee for a period of time. They get to watch and learn our ways of doing things, then they do those things under direct supervision (the same process I have used in multiple industries and positions and I am now using as I build my home services business too).
If there are any problems we deal with them openly and honestly and immediately.
Technical problems can be fixed - attitudes can not. We proceed accordingly. Everything they do is noted and so long as they have the right attitude and mindset, we get their skills up to a level they can do the job effectively on their own as they learn.
We also make it clear that continuous training and skills development while always working to become better is part of our culture and is a mandatory requirement. Recognition and rewards for superior performance are as well - and this has served me very well for many years in all that I have done.
Good people are the difference - and that always begins with the company itself, how it views, attracts, screens, onboards, trains, rewards and retains people.
I like your way of assessing them in the field and noting how they act, treat people and treat you. If they leave trach in your vehicle then its obvious they are going to do such things and anger your customers too.