I once flew with an ATPL holder, 10,000+hrs captain for a well known airline, I genuinely felt like he was trying to kill me during his first approach.
Certainly, those pilots are out there, hence my remark:
But a very experienced pilot, competent in light single GA 'planes, can generally check themselves out in a similar type certified GA type without problem.
You want to be assured that the pilot (instructor) is current in the class of aircraft under consideration. Some big iron pilots are very certainly out of touch with flying light aircraft. Hopefully, they are not offering mentoring services in those types!
Otherwise, a pilot is entitled to refamiliarize themselves in a less familiar type, while being current. Their first landing may be excused from perfection. I checked myself out in the Super Cub on skis the other day, I had not flown it on skis in ten months. I was not proud of my first landing, but the next six were very pleasing. But the same afternoon, I flew as mentor to another pilot, while he flew eight circuits.
It can be common that a pilot not fly a type for a while (like seasonal float flying). It is their duty to assure they are ready for their first next flight. This may be by seeking a checkout, or just being extra careful for a self checkout.